Planning Robot Stopping Points to Avoid Collisions

ABSTRACT

An example method includes determining a path to be followed by a vehicle through an environment. The path includes an ordered sequence of positions. The method also includes determining an intersection between a first object in the environment and a first area planned to be occupied by the vehicle while moving along the path and, in response, sequentially testing the ordered sequence of positions to identify a first ordinal position in the ordered sequence of positions, where the first ordinal position corresponds to a second area planned to be occupied by the vehicle while moving along the path, and where the second area is within a threshold distance of the first object. The method further additionally includes trimming the path to remove (i) the first ordinal position and (ii) any positions subsequent thereto and causing the vehicle to stop at an end of the trimmed path.

BACKGROUND

A warehouse may be used for storage of goods by a variety of differenttypes of commercial entities, including manufacturers, wholesalers, andtransport businesses. Example stored goods may include raw materials,parts or components, packing materials, and finished products. In somecases, the warehouse may be equipped with loading docks to allow goodsto be loaded onto and unloaded from delivery trucks or other types ofvehicles. The warehouse may also use rows of pallet racks to allow forstorage of pallets, which are flat transport structures that containstacks of boxes or other objects thereon. Additionally, the warehousemay use machines or vehicles for lifting and moving goods or pallets ofgoods, such as cranes, forklifts, and pallet jacks. Human operators maybe employed to operate machines, vehicles, and other equipment. In somecases, one or more of the machines or vehicles may be robotic devicesguided by computer control systems.

SUMMARY

In an example embodiment, a path may be determined for a vehicle tocarry out a task in an environment. The path, which includes an orderedsequence of positions, may be evaluated for potential collisions betweenthe vehicle and objects within the environment by determining aplurality of vehicle footprints representing areas within theenvironment expected or planned to be occupied by the vehicle whilemoving along the path. A buffer region may be placed around any objectswithin the environment that intersect with one or more of the vehiclefootprints. The buffer regions may be used to determine a first ordinalposition along the path that corresponds to a vehicle footprintintersecting with one or more buffer regions. The path may then betrimmed to remove, from the ordered sequence of positions, the firstordinal position and any positions subsequent thereto, thereby removingpositions predicted to result in a collision. The vehicle may follow thetrimmed path and stop at an end thereof. Alternative paths following thetrimmed path may be determined to navigate the vehicle around theobstacles.

In a first embodiment, a method is provided that includes determining,by a control system, a path to be followed by a vehicle through anenvironment. The path includes an ordered sequence of positions. Themethod also includes determining, by the control system, an intersectionbetween a first object in the environment and a first area planned to beoccupied by the vehicle while moving along the path and, in response,sequentially testing, by the control system, the ordered sequence ofpositions to identify a first ordinal position in the ordered sequenceof positions, where the first ordinal position corresponds to a secondarea planned to be occupied by the vehicle while moving along the path,where the second area is within a threshold distance of the firstobject, and where all areas planned to be occupied by the vehicle atpositions of the ordered sequence of positions preceding the firstordinal position are beyond the threshold distance of the first object.The method additionally includes trimming, by the control system, thepath to remove, from the ordered sequence of positions, (i) the firstordinal position and (ii) any positions subsequent thereto. The methodfurther includes causing, by the control system, the vehicle to stop atan end of the trimmed path.

In a second embodiment, a system is provided that includes a vehicle anda control system. The control system is configured to determine a pathto be followed by the vehicle through an environment. The path comprisesan ordered sequence of positions. The control system is also configuredto determine an intersection between a first object in the environmentand a first area planned to be occupied by the vehicle while movingalong the path and, in response, sequentially test the ordered sequenceof positions to identify a first ordinal position in the orderedsequence of positions, where the first ordinal position corresponds to asecond area planned to be occupied by the vehicle while moving along thepath, where the second area is within a threshold distance of the firstobject, and where all areas planned to be occupied by the vehicle atpositions of the ordered sequence of positions preceding the firstordinal position are beyond the threshold distance of the first object.The control system is additionally configured to trim the path toremove, from the ordered sequence of positions, (i) the first ordinalposition and (ii) any positions subsequent thereto. The control systemis further configured to cause the vehicle to stop at an end of thetrimmed path.

In a third embodiment, a non-transitory computer readable storage mediumis provided having stored thereon instructions that, when executed by acomputing device, cause the computing device to perform operations. Theoperations include determining a path to be followed by a vehiclethrough an environment. The path comprises an ordered sequence ofpositions. The operations also include determining an intersectionbetween a first object in the environment and a first area planned to beoccupied by the vehicle while moving along the path and, in response,sequentially testing the ordered sequence of positions to identify afirst ordinal position in the ordered sequence of positions, where thefirst ordinal position corresponds to a second area planned to beoccupied by the vehicle while moving along the path, where the secondarea is within a threshold distance of the first object, and where allareas planned to be occupied by the vehicle at positions of the orderedsequence of positions preceding the first ordinal position are beyondthe threshold distance of the first object. The operations additionallyinclude trimming the path to remove, from the ordered sequence ofpositions, (i) the first ordinal position and (ii) any positionssubsequent thereto. The operations further include causing the vehicleto stop at an end of the trimmed path.

In a fourth embodiment, a system is provided that includes means fordetermining a path to be followed by a vehicle through an environment.The path comprises an ordered sequence of positions. The system alsoincludes means for determining an intersection between a first object inthe environment and a first area planned to be occupied by the vehiclewhile moving along the path and, in response, sequentially testing theordered sequence of positions to identify a first ordinal position inthe ordered sequence of positions, where the first ordinal positioncorresponds to a second area planned to be occupied by the vehicle whilemoving along the path, where the second area is within a thresholddistance of the first object, and where all areas planned to be occupiedby the vehicle at positions of the ordered sequence of positionspreceding the first ordinal position are beyond the threshold distanceof the first object. The system additionally includes means for trimmingthe path to remove, from the ordered sequence of positions, (i) thefirst ordinal position and (ii) any positions subsequent thereto. Thesystem further includes means for causing the vehicle to stop at an endof the trimmed path.

These as well as other embodiments, aspects, advantages, andalternatives will become apparent to those of ordinary skill in the artby reading the following detailed description, with reference whereappropriate to the accompanying drawings. Further, it should beunderstood that this summary and other descriptions and figures providedherein are intended to illustrate embodiments by way of example onlyand, as such, that numerous variations are possible. For instance,structural elements and process steps can be rearranged, combined,distributed, eliminated, or otherwise changed, while remaining withinthe scope of the embodiments as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a system, in accordance withexample embodiments.

FIG. 2 illustrates a block diagram of a system for operating one or morewarehouses, in accordance with example embodiments.

FIG. 3 illustrates a block diagram of a system, in accordance withexample embodiments.

FIG. 4 illustrates a robotic device architecture for one or more roboticdevices, in accordance with example embodiments.

FIG. 5 illustrates a laser scanner architecture for one or more roboticdevices, in accordance with example embodiments.

FIG. 6A illustrates a block diagram of an example computing device, inaccordance with example embodiments.

FIG. 6B illustrates a network of computing clusters arranged as acloud-based server system, in accordance with example embodiments.

FIG. 7 illustrates a flow chart, in accordance with example embodiments.

FIG. 8A illustrates a path through an environment, in accordance withexample embodiments.

FIG. 8B illustrates vehicle footprints, in accordance with exampleembodiments.

FIG. 8C illustrates an obstacle buffer, in accordance with exampleembodiments.

FIG. 8D illustrates a trimmed path, in accordance with exampleembodiments.

FIG. 8E illustrates alternative paths, in accordance with exampleembodiments.

FIG. 9 illustrates protective and warning fields of a vehicle, inaccordance with example embodiments.

FIG. 10A illustrates a velocity trajectory, in accordance with exampleembodiments.

FIG. 10B illustrates an alternative velocity trajectory, in accordancewith example embodiments.

FIG. 11A illustrates another path through an environment, in accordancewith example embodiments.

FIG. 11B illustrates additional vehicle footprints and an obstaclebuffer, in accordance with example embodiments.

FIG. 11C illustrates another trimmed path, in accordance with exampleembodiments.

FIG. 12 illustrates obstacles in warning fields of a vehicle, inaccordance with example embodiments.

DETAILED DESCRIPTION

Example methods, devices, and systems are described herein. It should beunderstood that the words “example” and “exemplary” are used herein tomean “serving as an example, instance, or illustration.” Any embodimentor feature described herein as being an “example” or “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments or features unless indicated as such. Other embodiments canbe utilized, and other changes can be made, without departing from thescope of the subject matter presented herein.

Thus, the example embodiments described herein are not meant to belimiting. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations.

Throughout this description, the articles “a” or “an” are used tointroduce elements of the example embodiments. Any reference to “a” or“an” refers to “at least one,” and any reference to “the” refers to “theat least one,” unless otherwise specified, or unless the context clearlydictates otherwise. The intent of using the conjunction “or” within adescribed list of at least two terms is to indicate any of the listedterms or any combination of the listed terms.

The use of ordinal numbers such as “first,” “second,” “third” and so onis to distinguish respective elements rather than to denote a particularorder of those elements. For purpose of this description, the terms“multiple” and “a plurality of” refer to “two or more” or “more thanone.”

Further, unless context suggests otherwise, the features illustrated ineach of the figures may be used in combination with one another. Thus,the figures should be generally viewed as component aspects of one ormore overall embodiments, with the understanding that not allillustrated features are necessary for each embodiment. In the figures,similar symbols typically identify similar components, unless contextdictates otherwise. Further, unless otherwise noted, figures are notdrawn to scale and are used for illustrative purposes only. Moreover,the figures are representational only and not all components are shown.For example, additional structural or restraining components might notbe shown.

Additionally, any enumeration of elements, blocks, or steps in thisspecification or the claims is for purposes of clarity. Thus, suchenumeration should not be interpreted to require or imply that theseelements, blocks, or steps adhere to a particular arrangement or arecarried out in a particular order.

I. Overview

Robotic navigation in an environment such as a warehouse can allowautonomous robotic devices the ability to carry out one or more actionswithout the need for constant human control. When a robotic device isgiven a task, a corresponding path through the environment andtrajectory for traversing the path may be determined for the task. Thepath may include an ordered sequence of locations or positions for therobotic device within the environment. The trajectory may includetiming, speed, and orientation of the robotic device for each of thepositions along the path.

In example embodiments, the robotic device may be a vehicle such as apallet jack or fork truck. Paths for the vehicle may be planned withknowledge of fixed objects (e.g., pallet racks, walls) in theenvironment. Therefore, the planned paths may generally not intersectwith such known fixed objects. Similarly, movements of multipleautonomous vehicles within the environment may be coordinated by acentralized path planner. Thus, the planned paths and trajectories ofthe autonomous vehicle may generally avoid collisions with otherautonomous vehicles. The known fixed objects and other vehicles may bevery unlikely to protrude into the planned paths for the vehicle in amanner that would be difficult to detect with sensors on the vehicle.

Nevertheless, movable and mobile objects may sometimes end up in theplanned paths of the autonomous vehicle. Particularly, in acollaborative system where both autonomous and human-operated vehicleswork in a shared environment, the human-operated vehicles may sometimesintersect with or be in the planned path of the autonomous vehicle.Additionally, such unexpected movable or mobile obstacles may sometimeshave physical parts or portions protruding therefrom. Such protrudingparts may, in some instances, be difficult to detect. For example, thetines of a human-operated vehicle may be located very close to theground, and may therefore be below a field of view of sensors on theautonomous vehicle or may be difficult to distinguish from the groundsurface of the environment. These difficult-to-detect protrudingphysical parts could extend into the planned path of the autonomousvehicle and potentially cause collisions.

Accordingly, before and/or while the vehicle traverses the path, thepath may be evaluated for collisions between the vehicle and objectswithin the environment. A map of the environment may be determined basedon data from sensors on the vehicle, sensors on other vehicles, and/orsensors within the environment, and may indicate objects within theenvironment. The map may be used to determine any intersections betweenobjects within the environment and areas planned to be occupied by thevehicle while moving along the path.

To determine whether any of the objects constitute obstacles along thepath, a plurality of vehicle footprints representing areas within theenvironment expected to be occupied by the vehicle may be projectedalong the path. These vehicle footprints may be used as a filter toidentify which of the objects indicated by the map are potentialobstacles. Specifically, intersections between the vehicle footprintsand the objects may be determined to identify expected collisions.Objects that intersect with at least one vehicle footprint may beconsidered potential obstacles, while objects that do not intersect withany vehicle footprint might not constitute obstacles. An intersectionbetween an object and a vehicle footprint may be used as a proxy signalindicative of an obstacle likely to have unexpected anddifficult-to-detect protruding physical parts that should be avoided.

A buffer region may be placed around each of the objects identified asan obstacle. The buffer region may operate to enforce a minimum distance(i.e., a first threshold distance) away from the obstacle at which thevehicle is to stop to avoid colliding with the obstacle. The minimumdistance may be based on a size of the obstacle, a type orclassification of the obstacle, a speed of the vehicle, a size of thevehicle, a load carried by the vehicle, and/or a task assigned to thevehicle, among other factors.

Notably, placing buffers around every obstacle in the environment wouldresult in a lot of false-positive detections of potential collisions,thus make navigation inefficient or impossible. Applying buffer regionsto objects after, rather than before, identifying them as obstaclesallows the number of false-positive collision detections to be reducedwhile allowing obstacles appearing in the vehicle's planned path to beused as a proxy for obstacles likely to have difficult-to-detect orunexpected protrusions that should be avoided or navigated around. Asimilar benefit may be derived from applying the buffer regions to theobjects after identifying them as potential obstacles, rather than byapplying a buffer region around the projected vehicle footprints beforedetermining intersections between objects and the footprints.

The buffer region may be used to identify a first ordinal position alongthe path whose corresponding vehicle footprint intersects with a bufferregion of at least one of the obstacles. Positions subsequent to thefirst ordinal position along the path may be associated with vehiclefootprints that intersect with obstacles or with the buffers around theobstacles, and may thus be at risk of collision On the other hand,positions before the first ordinal position along the path may beassociated with vehicle footprints that do not intersect with obstaclesor with the buffers around the obstacles. That is, the buffer region maybe used to identify the first position along the path likely to resultin a collision. Accordingly, to avoid collisions, the path may betrimmed to remove, from the ordered sequence of positions, the firstordinal position and any positions subsequent thereto.

The vehicle may be caused to follow the trimmed path and stop at an endthereof, thus avoiding collisions with obstacles within the environment,including obstacles that may have difficult-to-detect parts protrudinginto the vehicle's path. A trajectory may be determined for the trimmedpath to cause the vehicle to slow down and stop at the end of thetrimmed path.

In some embodiments, in addition to determining vehicle footprints toindicate areas within the environment planned to be occupied by thevehicle within a future time period, object footprints may be determinedfor each of the mobile objects within the environment. The objectfootprints may be based on expected paths of the mobile objects throughthe environment, and may indicate areas within the environment expectedto be occupied by the objects within the future time period.Intersections may then be determined between the vehicle footprints andthe mobile object footprints to identify potential collisions. Theintersections may be determined in space (i.e., a vehicle footprintintersects with an object footprint, regardless of timing), or in bothspace and time (i.e., a vehicle footprint intersects with an objectfootprint, and both footprints represent vehicle/object positions at thesame future point in time). Buffer regions may then be applied to anyobjects or object footprints that are determined to intersect with atleast one vehicle footprint.

II. Example System Design

FIG. 1 is a block diagram of system 100, in accordance with exampleembodiments. System 100 includes planning system 110 and robotic device120. Planning system 110 can include offboard planner 112 that cancoordinate motion of one or more robotic devices operating in anenvironment. Offboard planner 112 can include roadmap planner 114.Offboard planner 112 and/or roadmap planner 114 can generate one or moreasynchronous paths 116 for a robotic device, such as robotic device 120,to follow while operating in an environment.

A roadmap graph, prototype graph, or other roadmap representing anenvironment can be received, determined, or otherwise provided toplanning system 110, offboard planner 112 and/or roadmap planner 114.Asynchronous paths 116 can be one or more paths based on the roadmapgraph, prototype graph, or other roadmap. For example, if the roadmapgraph, prototype graph, or other roadmap has a plurality of edges thatconnect a plurality of intersections, asynchronous paths 116 can bespecified in terms of the plurality of edges and/or the plurality ofintersections.

Robotic device(s) 120 can include onboard software 130 and/or hardware150. Onboard software 130 can include one or more of: localizationsubsystem 132, obstacle detection subsystem 134, odometry subsystem 136,path-following subsystem 138, and trajectory-following subsystem 142.Localization subsystem 132 can be used to localize a robotic device,that is, determine a location of the robotic device within anenvironment. Localization subsystem 132 can generate position estimatesof the robotic device and/or other objects that can be used to localizethe robotic device, assist the robotic device in following a path, suchas asynchronous paths 116, and/or assist the robotic device in followinga trajectory, such as trajectories 140. Once the position estimates aregenerated, localization subsystem 132 can provide the position estimatesto path-following subsystem 138.

An asynchronous path, or path for short, can be a time-invariant plan orother information indicating how robotic device 120 can travel from astarting point SP to an ending point EP; i.e., an (asynchronous) pathdoes not take time into account. In contrast, a trajectory can includevalues of a steering angle and of traction motor velocity that roboticdevice 120 can follow for a planning time interval.

The planning time interval can be a duration of time that a roboticdevice is guided, or planned to follow a path, route, and/or travel. Insome embodiments, the planning time can be a predetermined amount oftime; e.g., five seconds, one second, 0.2 seconds, or 0.1 seconds. Forexample, a predetermined planning time interval can be determined basedon a user input that specifies a value for the planning time interval.In other embodiments, the planning time interval can be determined basedon one or more other values; e.g., a stitch time, a time associated witha uniform edge (or path) cost, an estimated time to travel along atrajectory. Other techniques for determining the planning time intervaland values for the planning time interval are possible as well.

Then, one or more trajectories can be used to describe how roboticdevice 120 can travel from starting point SP to an ending point EP in atime-variant manner. In some embodiments, a trajectory can also provideinformation about values of other variables than a steering angle and atraction motor velocity over the planning time interval, such as, butnot limited to, other kinematic variables (e.g., velocity andacceleration) of robotic device 120, and actuator positions of roboticdevice 120.

As an example, a path to drive a car from a location “home” to alocation “work” may include an ordered listing of streets that a controlentity, such as a person or control device of an autonomous vehicle, canuse to drive the car from home to work. In this example, a trajectoryfrom home to work can involve one or more instructions specifyingvelocity and/or acceleration that the control entity can use to drivethe car from home to work. In some examples, the trajectory can taketraffic, obstacles, weather, and other time-sensitive conditions intoaccount; e.g., the trajectory to go from home to work can indicate thatthe control entity “turn right for 10 seconds at 20 MPH or less”,“accelerate to 55 MPH and drive straight for 3 minutes”, “slow to 20 MPHwithin 30 seconds”, “turn left for 10 seconds at 20 MPH or less”, etc.In some embodiments, the trajectory can be changed along the way; e.g.,to account for obstacles, changes in path, etc.

Obstacle detection subsystem 134 can determine whether one or moreobstacles are blocking a path and/or a trajectory of robotic device 120.Examples of these obstacles can include, but are not limited to,pallets, objects that may have fallen off a pallet, robotic devices, andhuman operators working in the environment. If an obstacle is detected,obstacle detection subsystem 134 can provide one or more communicationsindicating obstacle detection to path-following subsystem 138. The oneor more communications indicating obstacle detection can includelocation information about one or more positions of one or moreobstacles detected by obstacle detection subsystem 134 and/oridentification information about the one or more obstacles detected byobstacle detection subsystem 134. Odometry subsystem 136 can use data,such as data from servo drives 152, to estimate one or more changes inposition of robotic device 120 over time.

Path-following subsystem 138 and/or trajectory-following subsystem 142can act as a planner aboard robotic device 120. This onboard planner canfollow one or more paths, such as asynchronous paths 116, based onposition estimates provided by localization subsystem 132.

Path-following subsystem 138 can receive asynchronous paths 116,position estimate inputs from localization subsystem 132, locationinformation about one or more positions of one or more obstacles fromobstacle detection subsystem 134, and/or information about one or morechanges in position from odometry subsystem 136, and generate one ormore trajectories 140 as outputs.

Hardware 150 can include servo drives 152 and/or motors 154. Servodrives 152 can include one or more servo drives. Servo drives 152 caninclude an electronic amplifier used to power one or moreservomechanisms and/or can monitor feedback signals from theservomechanism(s). Servo drives 152 can receive control signals, such astrajectories 144, from onboard software 130, and can provide electriccurrent to the servomechanism(s) to produce motion proportional to thecontrol signals. In some embodiments, servo drives 152 can comparestatus information received from the servomechanism(s) with an expectedstatus as commanded by trajectories 144. Then, servo drives 152 canadjust a voltage frequency or pulse width of the provided electriccurrent to correct for deviations between received status informationand an expected status. In other embodiments, servo drives 152 canprovide information, such as the feedback signals and/orlocation-related information, to onboard software 130.

One or more motors 154 can be part or all of the servomechanism(s)powered by servo drives 152. For example, motors 154 can use theelectric current provided by servo drives 152 to generate mechanicalforce to drive part or all of robotic device 120; e.g., motors 154 canprovide force to propel robotic device 120 and/or drive one or moreeffectors of robotic device 120.

Path planning of robotic devices within an environment, such as anenvironment that includes indoor settings, such as a warehouse, officebuilding, or home, and/or outdoor settings, such as a park, parking lot,or yard, can be performed with respect to a roadmap graph, which is aconnected graph of paths that agents, such as robotic devices, mayfollow. Using roadmap graphs to plan agent routing within theenvironment rather than taking a free-space approach can reduce a totalplanning state space and so making large-scale multi agent coordinationtractable. Further, the use of roadmap graphs can enable operators tointuitively control areas in which robotic devices are allowed tonavigate.

Roadmap graph generation can first involve generation of a prototypegraph, which indicates the rough position of lanes and directions oftravel. In some examples, a prototype graph can be a directed graph thatindicates lanes and directions of travel of robotic devices. In otherexamples, a prototype graph can be generated manually based on a map ordrawing of the environment.

FIG. 2 depicts system 200 for operating one or more warehouses, inaccordance with example embodiments. System 200 includes warehousemanagement system 210, planning system 110, and robotic device 120.Warehouse management system 210 can receive one or more logisticsrequests 212 associated with the warehouse; e.g., requests to store oneor more items in the warehouse and/or requests to ship one or more itemsfrom the warehouse. Warehouse management system 210 can translatelogistics requests 212 into one or more actions 214, where actions 214can include, but are not limited to, a “move-to” action to move one ormore designated agents to one or more designated locations, and a“transport” action to carry one or more items to one or more designatedlocations. In some examples, actions 214 can be go-to commands of theform {agent ID, destination}, but other actions are possible such asmove pallet. These are typically decomposable into move-to commands,however (move to pick location, move to place location).

Planning system 110 includes offboard planner 112 and executor 220.Offboard planner 112 can receive actions 214 as inputs and generate oneor more coordinated paths 216 for one or more agents operating in awarehouse; e.g., multiple robotic devices, to carry out actions 214.Coordinated paths 216 can be part of a coordinated action plan for allagents in the warehouse to fulfill logistics requests 212. Thecoordinated action plan can take precedence of agents into account;e.g., if robotic devices RD1 and RD2 are both expected to reach a pointat approximately the same time, one of the robotic devices can haveprecedence or priority over the other, such as robotic device RD1waiting for robotic device RD2 to pass through the point (or viceversa). Executor 220 can receive coordinated paths 216 and generatenon-conflicting sub-paths 222 to direct robotic device 120 inaccomplishing its part of the coordinated action plan to carry outactions 214 to fulfill logistics requests 212.

As illustrated above in FIG. 2, planning system 110, which includesoffboard planner 112 and executor 220, can communicate with roboticdevice 120. In some embodiments, the robotic device can be a fork truck,such as any OSHA class 1 or class 3 powered industrial truck. In otherembodiments, planning system 110 can include software that executesusing one or more networked computing devices located in the “cloud”(e.g., one or more networked computing devices) and/or located somewhereon a premises co-located with robotic device 120.

In some embodiments, offboard planner 112 and executor 220 can besynchronized. In an example embodiment, offboard planner 112 andexecutor 220 can be implemented on one device; e.g., in planning system110 or robotic device 120, and synchronized within the device. Inanother example embodiment, offboard planner 112 and executor 220 canact synchronously in one or more devices.

FIG. 3 illustrates a system 300 that includes warehouse managementsystem 210, and one or more robotic devices 120 connected using network318, in accordance with example embodiments. Inventory task instructionsmay be provided to warehouse management system 210 via network 318regarding movement of objects, such as pallets, and/or robotic devicesto warehouse management system 210. An example inventory task can be tobring pallet A containing items of type B to location C.

Warehouse management system 210 can receive the inventory taskinstructions and generate one or more task/mission instructions (e.g.,an instruction to robotic device A to move pallet B from location C tolocation D) and/or plans for controlling robotic device(s) 120 to carryout the inventory task instructions. The task/mission instructionsand/or plans can include information about one or more paths and/or oneor more trajectories, where the task/mission instruction(s), plan(s),path(s) and trajectory/trajectories are generated by planning system 110of warehouse management system 210 using the techniques discussed in thecontext of FIGS. 1, 2, and 7-11.

For example, warehouse management system 210 can be a centralizedcontrol service running on and storing data using one or more computingdevices; e.g., server computing devices. To perform these tasks,warehouse management system 210 can include WMS middleware and canprovide a user interface to provide access to tools for monitoring andmanaging system 300. The WMS middleware and/or other components ofwarehouse management system 210 can use one or more applicationprogramming interfaces (APIs), such as protocol conversion APIs forconversion between task/mission instructions (e.g., an instruction torobotic device A to move pallet B from location C to location D) torobotic device paths, poses, and/or trajectories; conversion betweeninventory tasks and task/mission instructions; and conversions betweenAPIs.

The user interface provided by warehouse management system 210 canprovide one or more user interface functions for system 300, including,but not limited to: monitoring of robotic device(s) 120, e.g.,presenting data related to location, battery status, state of charge,etc. of one or more robotic devices; enabling generation and sending ofinventory task instruction(s), task/mission instruction(s), plan(s),path(s) and/or trajectory/trajectories to one or more of roboticdevice(s) 120; and reviewing, updating, deletion, and/or insertion ofdata related to one or more warehouse maps, pallets, networks, and/orplanning systems (e.g., planning system 110 and/or warehouse managementsystem 210).

In some embodiments, warehouse management system 210 can store,generate, read, write, update, and/or delete data related to system 300,such as, but not limited to: data regarding completion of a task/missioninstruction by one or more of robotic device(s) 120; data regardinglocations and/or poses of some or all of robotic device(s) 120,including data indicating a location where a robotic device wasinitialized/booted; data related to one or more audit trails for humanactions, incident analysis, and/or debugging; and data for statetracking. In other embodiments, warehouse management system 210 caninclude a central message router/persistence manager that communicateswith robotic device(s) 120 and one or more adapters. Each of the one ormore adapters can provide access to data and/or communications of system300 available to warehouse management system 210, and can include, butare not limited, to: a user interface service adapter for theabove-mentioned user interface, a web content service adapter enablingWorld Wide Web (WWW)/Internet access to information about system 300, amessage proxy adapter and/or a WMS adapter to act as intermediariesbetween communications between APIs and/or the WMS.

FIG. 3 shows that each of the one or more robotic devices 120 caninclude one or more of: onboard system 320, network switch 330, vehiclecontroller 332, programmable logic controller (PLC) 334, one or moredevice sensors 338, and one or more drives 340.

Onboard system 320 can be a computation and sensor package for roboticplanning configured for installation into and use with robotic device120, where onboard system 320 can include onboard sensors 322 and one ormore planning/execution processors 324. FIG. 3 also shows that onboardsystem 320 is configured to use network switch 330 at least tocommunicate with planning system 110 (via network 318), with devicesensors 338, and/or with one or more actuators of robotic device 120.

Onboard system 320 can be responsible for one or more of: localizationof robotic device 120, generation of local trajectories to carry outplans and/or travel along paths and/or trajectories provided bywarehouse management system 210, generation of commands to drives 340 tofollow one or more (local) trajectories, generation of commands tocontrol actuator(s) of robotic device 120, and reporting pose, statusand/or other information to warehouse management system 210.

Onboard sensors 322 can include one or more navigation lasers, laserscanners, cameras, and/or other sensors for navigating and/orcontrolling onboard system 320. For example, a robotic device of roboticdevice(s) 120 can include one or more laser scanners, such as one ormore laser scanners provided by SICK AG of Waldkirch, Germany, HOKUYOAUTOMATIC CO. LTD of Osaka, Japan, or KEYENCE CORPORATION of Osaka,Japan. The laser scanners can be used for obstacle detection and/oravoidance along a direction of travel of the robotic device as well asalong the sides, corners, and/or back of the robotic device. The laserscanners can also be used to localize the robotic device usingreflector-based localization. In some embodiments, cameras and/or othersensors can be used for obstacle detection, obstacle avoidance, and/orlocalization instead of or along with the laser scanners.

Planning/execution processor(s) 324 can include one or more computerprocessors connected at least to onboard sensors 322. Planning/executionprocessor(s) 324 can read data from onboard sensors 322, generate localtrajectories and/or commands to drive(s) 340 to move robotic device 120,and communicate with warehouse management system 210. A local trajectorycan be a trajectory where robotic device 120 starts at a starting poseand reaches an ending pose at some time. In some examples, the startingpose can be implicitly specified; e.g., the starting pose can be acurrent pose of robotic device 120 and so the local trajectory be basedon an assumption that its starting pose is the current pose of roboticdevice 120.

Planning/execution processor(s) 324 can utilize a component framework.The component framework can be a multi-threaded job scheduling andmessage passing system built on software libraries for input/output(I/O) and signaling configured to provide a consistent asynchronousmodel of robotic device 120, such as the “boost::asio” and“boost::signals2” software libraries provided by boost.org of Onancock,Va. The component framework can enable communication between softwarecomponents (or modules) so that the software components can be executedin parallel in a thread safe manner.

The component framework can include one or more of: a state machinecomponent, a localization component, a planning component, and atrajectory following component. The state machine component can manage astate of robotic device 120 for vehicle initialization, vehiclecommanding and fault handling. The state machine component can use adeterministic finite automaton or other state machine to manage thestate of the robotic device.

The localization component can read data from vehicle sensors andintegrate prior state information of robotic device 120 to determine apose of robotic device 120. The pose can be determined relative to oneor more detected landmarks/points of interest, such as pallets or otherobjects. The planning component can receive one or more objectives fromwarehouse management system 210 and determine a local trajectory forrobotic device 120 to achieve those objectives. In some embodiments, thelocal trajectory can be a short-term trajectory that robotic device 120is to follow for a predetermined amount of time; e.g., 100 milliseconds,200 milliseconds, 500 milliseconds, 1 second, 5 seconds. The trajectoryfollowing component can receive the local trajectory generated by theplanning component, and generate drive control instructions to travelalong the local trajectory. The drive control instructions that are thenrelayed to drives 340 that control a traction motor and other actuatorsfor robotic device 120.

Network switch 330 can enable communications for robotic device(s) 120.These communications can include, but are not limited to, communicationsbetween onboard system 320 and the rest of robotic device 120; e.g.,device sensors 338 and drives 340, and communications with warehousemanagement system 210 via network 318. For example, network switch 330can enable Transmission Control Protocol/Internet Protocol(TCP/IP)-based communications over Ethernet and/or other wirelinecommunications interface(s) to a wireline network and/or over Wi-Fi™and/or other wireless communications interface(s) to a wireless network,such as a PLANET Ethernet Switch by PLANET Technology Corporation of NewTaipei City, Taiwan.

In some embodiments, communications between robotic device(s) 120 andplanning system 110 can include remote procedure calls (RPCs). Theremote procedure calls can allow invocation of software procedures,methods, and/or functions resident on one or more of robotic device(s)120 by software of planning system 110 and vice versa. The remoteprocedure calls can be based on a communications protocol, such asTCP/IP, a HyperText Transfer Protocol (HTTP) such as HTTP 1.0 and/orHTTP 2.0, and/or another communications protocol. Some or all of theremote procedure calls can include encrypted data; such data may beencrypted using the Secure Sockets Layer (SSL), Transport Layer Security(TLS), and/or one or more other encryption algorithms and/or protocols.In embodiments where encrypted data is used, one or more certificationauthorities, such as a private certification authority, can authenticateone or more certificates used in encrypting and/or decrypting theencrypted data. A certificate authority can use an access control list(ACL) to control access to the one or more certificates. The remoteprocedure calls can use a request/response protocol and/or abidirectional streaming protocol for RPC-related communications. Inembodiments where the bidirectional streaming protocol is used forRPC-related communications, a single long-lived RPC can be used toimplement the bidirectional streaming protocol.

Vehicle controller 332 and/or programmable logic controller 334 canprovide electrical and sensor management functionality for roboticdevice(s) 120. The electrical and sensor management functionality caninclude, but is not limited to, functionality for electrical loadcontrol, lighting control, sensor control, sensor and/or switch signalprocessing, and power management. Vehicle master 336 can providefunctionality for controlling one or more actuators, such as liftdevices, of robotic device(s) 120.

Device sensor(s) 338 can include one or more sensors that can providedata related to controlling and/or operating robotic device(s) 120. Thedata can provide information about an environment about roboticdevice(s) 120, such as but not limited to, localization information,position estimates, and mapping data. For example, device sensor(s) 338can include one or more lasers (e.g., two-dimensional (2D) lasers,safety lasers, laser scanners), cameras (e.g., Time-of-Flight (ToF)cameras, Red-Green-Blue (RGB) cameras, thermal cameras), electricalsensors, proximity sensors, navigational devices, and location sensors.

Drive(s) 340 can include one or more drive controllers and/or actuatorsthat provide functionality for moving robotic device(s) 120. The drivecontrollers can direct the drive actuators to control movement ofrobotic device(s) 120. The drive actuators can include one or moretraction motors, electric drives, hydraulic drives, and pneumaticdrives.

FIG. 4 illustrates robotic device architecture 400 of robotic device(s)120, in accordance with example embodiments. Robotic device architecture400 of robotic device(s) 120 can include software. The software caninclude software for localization 410, software for a pallet poseestimator 412, software related to state machine 414, software forplanner follower 416, software for component framework 420 and softwarefor operating system 430. The software can be executed by one or morehardware planning/execution processors 324. Communications betweenrobotic device(s) 120 and other devices can be carried out using networkgateway 440 and/or network switch 330. For example, network gateway 440can be used for wireless communications with and within a robotic deviceof robotic device(s) 120 and network switch 330 can be used for wirelinecommunications with and within a robotic device of robotic device(s)120. Robotic device architecture 400 also includes additional hardwaresuch as device sensor(s) 338 and drive(s) 340 discussed above in thecontext of FIG. 3. In some embodiments, robotic device architecture 400can include one or more cameras, including but not limited to, ToFcamera 450 and RGB camera 452, where the one or more cameras can includeone or more still cameras and/or one or more video cameras.

FIG. 5 illustrates laser scanner architecture 500 for robotic device(s)120, in accordance with example embodiments. In some embodiments, someor all of device sensor(s) 338 can be lasers and laser scannersillustrated by laser scanner architecture 500.

Laser scanner architecture 500 can include lasers 510 and 512, laserscanner 524, protocol converter 526, network switch 330, and onboardsystem 320. Lasers 510 and 512 can be located at fixed positions ofrobotic device(s) 120; for example, laser 510 can be located at thefront of a robotic device and laser 512 can be located at the rear ofthe robotic device. In some embodiments, additional lasers can belocated at, for example, the sides and/or corners of the robotic device.Lasers 510 and 512 and/or laser scanner 524 can provide information tolocalize the robotic device within an environment. In some embodiments,lasers 510 and 512 and/or laser scanner 524 can emit light that isreflected off of one or more reflectors—the reflected light can bedetected by one or more laser sensors, and the robotic device can belocalized within the environment based on a duration of time taken todetect the reflected light. In example embodiments, some or all oflasers 510 and 512 and/or laser scanner 524 can include one or morelaser sensors for detecting reflected laser light. Then, some or all oflasers 510 and 512 and/or laser scanner 524 can generate data, includingbut not limited to, data related to a laser (e.g., maintenance data forthe laser), data related to light emitted by the laser, and data relatedto one or more durations of time taken to detect reflected laser lightby the laser sensor(s).

As illustrated in FIG. 5, laser scanner 524 can be directly connected tonetwork switch 330, while lasers 510 and 512 can be connected to networkswitch 330 via protocol converter 526. However, in some embodiments,laser scanner 524 can be connected to network switch 330 via protocolconverter 526, and lasers 510 and 512 can be connected directly tonetwork switch 330, among other possible combinations. Protocolconverter 526 can convert a communications protocol used by a laser,such as laser 510 and/or 512, to a communications protocol used bynetwork switch 330; e.g., convert from a communications protocol basedon RS-422 to a communications protocol based on Ethernet. Then, lasers510 and 512 and laser scanner 524 can send data to and receive commandsfrom onboard system 320 via network switch 330 and perhaps protocolconverter 526.

In some embodiments, robotic device(s) 120 can be subject to one or morefailure conditions. Examples of those failure conditions and relatedrecovery strategies are described in Table 2 below.

TABLE 1 Name Summary Recovery Strategy Stale Localization Localizationsystem is unable Robotic device will halt and to determine roboticdevice notify human operator. The pose and/or localization operator canintervene by certainty estimate has manually driving robotic exceededbounds. device to a location for re- localization and reengaging.Trajectory Following Trajectory following error Robotic device will haltand exceeds threshold. attempt to restart trajectory followingautomatically. If system fails twice in a row then human operator willbe notified. The operator can intervene by manually driving roboticdevice back onto roadmap. No Safe Trajectory Due to obstacle proximity,the Robotic device will halt and trajectory planner cannot find notifyhuman operator. The a safe trajectory that would operator can interveneby keep the robotic device a safe manually driving robotic distance fromknown device around obstacle. obstacles. Hardware FaultSteering/traction drive fault or Robotic device will halt and otherlow-level hardware I/O notify human operator. The fault conditionoperator can power-cycle and manually drive robotic device back ontoroadmap. Pallet Detection Failure Robotic device expected to Roboticdevice will send discover a pallet at message to a control servicecommanded location; no that includes sensor data pallet was foundrelative to where the pallet was expected to be discovered. The controlservice will notify human operator and optionally may send pallet poseinformation manually. Pallet Pose Estimation Failure Robotic devicecould not Robotic device will send determine pose of pallet message to acontrol service relative to robotic device at that includes sensor datahigh confidence. relative to where the pallet was expected. The controlservice will notify human operator and send pallet pose informationmanually.

III. Example Computing Device Architecture

FIG. 6A is a functional block diagram of computing device 600 (e.g.,system, in accordance with example embodiments. Computing device 600shown in FIG. 6A can be configured to perform at least one functionrelated to one or more of: planning system 110, offboard planner 112,roadmap planner 114, robotic device 120, onboard software 130, hardware150, system 200, warehouse management system 210, executor 220, network318, onboard system 320, onboard sensors 322, planning/executionprocessors 324, network switch 330, central vehicle controller 332,programmable logic controller 334, vehicle master 336, device sensors338, drives 340, robotic device architecture 400, laser scannerarchitecture 500, and any other methods or operations herein described.Computing device 600 may include a user interface module 601, anetwork-communication interface module 602, one or more processors 603,data storage 604, one or more sensors 620, and one or more actuators630, all of which may be linked together via a system bus, network, orother connection mechanism 605. In some embodiments, computing device600 can be configured to act as part or all of a warehouse controlsystem.

User interface module 601 can be operable to send data to and/or receivedata from external user input/output devices. For example, userinterface module 601 can be configured to send and/or receive data toand/or from user input devices such as a keyboard, a keypad, a touchscreen, a computer mouse, a trackball, a joystick, a camera, a voicerecognition module, and/or other similar devices. User interface module601 can also be configured to provide output to user display devices,such as one or more cathode ray tubes (CRT), liquid crystal displays,light emitting diodes (LEDs), displays using digital light processing(DLP) technology, printers, light bulbs, and/or other similar devices,either now known or later developed. User interface module 601 can alsobe configured to generate audible output(s), such as a speaker, speakerjack, audio output port, audio output device, earphones, and/or othersimilar devices.

Network-communications interface module 602 can include one or morewireless interfaces 607 and/or one or more wireline interfaces 608 thatare configurable to communicate via a network. Wireless interfaces 607can include one or more wireless transmitters, receivers, and/ortransceivers, such as a Bluetooth™ transceiver, a Zigbee® transceiver, aWi-Fi™ transceiver, a WiMAX™ transceiver, and/or other similar type ofwireless transceiver configurable to communicate via a wireless network.Wireline interfaces 608 can include one or more wireline transmitters,receivers, and/or transceivers, such as an Ethernet transceiver, aUniversal Serial Bus (USB) transceiver, or similar transceiverconfigurable to communicate via a twisted pair wire, a coaxial cable, afiber-optic, link, or a similar physical Connection to a wirelinenetwork.

In some embodiments, network communications interface module 602 can beconfigured to provide reliable, secured, and/or authenticatedcommunications. For each communication described herein, information forensuring reliable communications (i.e., guaranteed message delivery) canbe provided, perhaps as part of a message header and/or footer (e.g.,packet/message sequencing information, encapsulation header(s) and/orfooter(s), size/time information, and transmission verificationinformation such as CRC and/or parity check values). Communications canbe made secure (e.g., be encoded or encrypted) and/or decrypted/decodedusing one or more cryptographic protocols and/or algorithms, such as,but not limited to, Data Encryption Standard (DES), Advanced EncryptionStandard (AES), an Rivest-Shamir-Adelman (RSA) algorithm, aDiffie-Hellman algorithm, a secure sockets protocol such as SecureSockets Layer (SSL) or Transport Layer Security (TLS), and/or DigitalSignature Algorithm (DSA), Other cryptographic protocols and/oralgorithms can be used as well or in addition to those listed herein tosecure (and then decrypt/decode) communications.

Processors 603 can include one or more general purpose processors,and/or one or more special purpose processors (e.g., digital signalprocessors, graphics processing units, application specific integratedcircuits, etc.). Processors 603 can be configured to executecomputer-readable program instructions 606 that are contained in thedata storage 604 and/or other instructions as described herein.

Data storage 604 can include one or more computer-readable storage mediathat can be read and/or accessed by at least one of processors 603. Theone or more computer-readable storage media can include volatile and/ornon-volatile storage components, such as optical, magnetic, organic orother memory or disc storage, which can be integrated in whole or inpart with at least one of processors 603. In some embodiments, datastorage 604 can be implemented using a single physical device (e.g., oneoptical, magnetic, organic or other memory or disc storage unit), whilein other embodiments, data storage 604 can be implemented using two ormore physical devices.

Data storage 604 can include computer-readable program instructions 606and perhaps additional data. In some embodiments, data storage 604 canadditionally include storage required to perform at least part of theherein-described methods and techniques and/or at least part of thefunctionality of the devices and networks.

In some embodiments, computing device 600 can include one or moresensors 620. Sensor(s) 620 can be configured to measure conditions in anenvironment for computing device 600 and provide data about thatenvironment. For example, sensor(s) 620 can include one or more of: (i)an identification sensor to identify other objects and/or devices, suchas, but not limited to, a Radio Frequency Identification (RFID) reader,proximity sensor, one-dimensional barcode reader, two-dimensionalbarcode (e.g., Quick Response (QR) code) reader, and a laser tracker,where the identification sensor(s) can be configured to readidentifiers, such as RFID tags, barcodes, QR codes, and/or other devicesand/or object configured to be read and provide at least identifyinginformation; (ii) a location sensor to measure locations and/ormovements of the computing device 600, such as, but not limited to, agyroscope, an accelerometer, a Doppler sensor, a Global PositioningSystem (GPS) device, a sonar sensor, a radar device, alaser-displacement sensor; and a compass; (iii) an environmental sensorto obtain data indicative of an environment of computing device 600,such as, but not limited to, an infrared sensor, an optical sensor, alight sensor, a camera, a biosensor, a capacitive sensor, a touchsensor, a temperature sensor, a wireless sensor, a radio sensor, amovement sensor, a microphone, a sound sensor, an ultrasound sensor;and/or a smoke sensor; and (iv) a force sensor to measure one or moreforces (e.g., inertial forces and/or G-forces) acting about thecomputing device 600, such as, but not limited to one or more sensorsthat measure: forces in one or more dimensions, torque, ground force,friction, and/or a zero moment point (ZMP) sensor that identifies ZMPsand/or locations of the ZMPs. Many other examples of sensor(s) 620 arepossible as well.

Computing device 600 can include one or more actuators 630 that enablecomputing device 600 to initiate movement. For example, actuator(s) 630can include or be incorporated with robotic joints connecting roboticlimbs to a robotic body. For example, actuator(s) 630 can includerespective robotic hip and robotic shoulder joints connecting respectiverobotic legs and arms to the robotic body. Further, the actuator(s) 630can include respective robotic knee joints connecting respectiveportions of the robotic legs (e.g., robotic thighs and robotic calves)and elbow joints connecting portions of the robotic arms (e.g., 52),robotic forearms and upper arms). Yet further, actuator(s) 630 caninclude respective robotic ankle joints connecting the robotic legs torobotic feet and respective robotic wrist joints connecting the roboticarms to robotic hands. In addition, actuator(s) 630 can include motorsfor moving the robotic limbs. As such, the actuator(s) 630 can enablemobility of computing device 600. Many other examples of actuator(s) 630are possible as well.

FIG. 6B depicts a network 614 of computing clusters 609 a, 609 b, 609 carranged as a cloud-based server system in accordance with exampleembodiments. Computing clusters 609 a, 609 b, 609 c can be cloud-baseddevices that store program logic and/or data of cloud-based applicationsand/or services; e.g., perform at least one function related to one ormore of: planning system 110, off board planner 112, roadmap planner114, robotic device 120 onboard software 130, hardware 150, system 200,warehouse management system 210, executor 220, network 318, onboardsystem 320, onboard sensors 322, planning/execution processors 324,network switch 330, central vehicle controller 332, programmable logiccontroller 334, vehicle master 336, device sensors 338, drives 340,robotic device architecture 400, laser scanner architecture 300, and anyother methods or operations herein described.

In some embodiments, computing clusters 609 a, 609 b, 609 c can be asingle computing device residing in a single computing center. In otherembodiments, computing clusters 609 a, 609 b, 609 c can include multiplecomputing devices in a single computing center, or even multiplecomputing devices located in multiple computing centers located indiverse geographic locations. For example, Figure GB depicts each ofcomputing clusters 609 a, 609 b, 609 c residing in different physicallocations.

In some embodiments, data and services at computing clusters 609 a, 609b, 609 c can be encoded as computer readable information stored innon-transitory, tangible computer readable media (or computer readablestorage media) and accessible by other computing devices. In someembodiments, computing clusters 609 a, 609 b, 609 c can be stored on asingle disk drive or other tangible storage media, or can be implementedon multiple disk drives or other tangible storage media located at oneor more diverse geographic locations.

In FIG. 6B, functionality of a planning system can be distributed amongthree computing clusters 609 a, 609 b, and 609 c. Computing cluster 609a can include one or more computing devices 600 a, cluster storagearrays 610 a, and cluster routers 611 a connected by a local clusternetwork 612 a. Similarly, computing cluster 609 b can include one ormore computing devices 600 b, cluster storage arrays 610 b, and clusterrouters 611 b connected by a local cluster network 612 b. Likewise,computing cluster 609 c can include one or more computing devices 600 c,cluster storage arrays 610 c, and cluster routers 611 c connected by alocal cluster network 612 c.

In some embodiments, each of the computing clusters 609 a, 609 b, and609 c can have an equal number of computing devices, an equal number ofcluster storage arrays, and an equal number of cluster routers. In otherembodiments, however, each computing cluster can have different numbersof computing devices, different numbers of cluster storage arrays, anddifferent numbers of cluster routers. The number of computing devices,cluster storage arrays, and cluster routers in each computing clustercan depend on the computing task or tasks assigned to each computingcluster.

In computing cluster 609 a, for example, computing devices 600 a can beconfigured to perform various computing tasks of a planning system, arobotic device, and/or a computing device. In one embodiment, thevarious functionalities of a planning system, a robotic device, and/or acomputing device can be distributed among one or more computing devices600 a, 600 b, and 600 c. Computing devices 600 b and 600 c in respectivecomputing clusters 609 b and 609 c can be configured similarly tocomputing devices 600 a in computing cluster 609 a. On the other hand,in some embodiments, computing devices 600 a, 600 b, and 600 c can beconfigured to perform different functions.

In some embodiments, computing tasks and stored data associated with aplanning system, a robotic device, and/or a computing device can bedistributed across computing devices 600 a, 600 b, and 600 c based atleast in part on the processing requirements of a roadmap editor, singleagent planning software, multiple agent planning software, a routingcomputing device, and/or a computing device, the processing capabilitiesof computing devices 600 a, 600 b, and 600 c, the latency, of thenetwork links between the computing devices in each computing clusterand between the computing clusters themselves, and/or other factors thatcan contribute to the cost, speed, fault-tolerance, resiliency,efficiency, and/or other design goals of the overall systemarchitecture.

The cluster storage arrays 610 a, 610 b, and 610 c, of the computingclusters 609 a, 609 b, and 609 c can be data storage arrays that includedisk array controllers configured to manage read and write access togroups of hard disk drives. The disk array controllers, alone or inconjunction with their respective computing devices, can also beconfigured to manage backup or redundant copies of the data stored inthe cluster storage arrays to protect against disk drive or othercluster storage array failures and/or network failures that prevent oneor more computing devices from accessing one or more cluster storagearrays.

Similar to the manner in which the functions of a planning system, arobotic device, and/or a computing device can be distributed acrosscomputing devices 600 a, 600 b, and 600 c of computing Clusters 609 a,609 b, and 609 c, various active portions and/or backup portions ofthese components can be distributed across cluster storage arrays 610 a,610 b, and 610 c. For example, some cluster storage arrays can beconfigured to store one portion of the data of a planning system, arobotic device, and/or a computing device can, while other clusterstorage arrays can store other portion(s) of data of a planning system,a robotic device, and/or a computing device. Additionally, some clusterstorage arrays can be configured to store backup versions of data storedin other cluster storage arrays.

The cluster routers 611 a, 611 b, and 611 c in computing clusters 609 a,609 b, and 609 c can include networking equipment configured to provideinternal and external communications for the computing clusters. Forexample, the cluster routers 611 a in computing cluster 609 a caninclude one or more internet switching and routing devices configured toprovide (i) local area network communications between the computingdevices 600 a and the cluster storage arrays 610 a via the local clusternetwork 612 a, and (ii) wide area network communications between thecomputing cluster 609 a and the computing clusters 609 b and 609 c viathe wide area network connection 613 a to network 614. Cluster routers611 b and 611 c can include network equipment similar to the clusterrouters 611 a, and cluster routers 611 b and 611 c can perform similarnetworking functions for computing clusters 609 b and 609 b that clusterrouters 611 a perform for computing cluster 609 a.

In some embodiments, the configuration of the cluster routers 611 a, 611b, and 611 c can be based at least in part on the data communicationrequirements of the computing devices and cluster storage arrays, thedata communications capabilities of the network equipment in the clusterrouters 611 a, 611 b, and 611 c, the latency and throughput of localnetworks 612 a, 612 b, 61.2 c, the latency, throughput, and cost of widearea network links 613 a, 613 b, and 613 c, and/or other factors thatcan contribute to the cost, speed, fault-tolerance, resiliency,efficiency and/or other design criteria of the moderation systemarchitecture.

IV. Example Obstacle Avoidance Operations

FIG. 7 illustrates flow chart 700 of example operations related toavoidance of obstacles by robotic device(s) 120. These operations may beexecuted by planning system 110, robotic devices 120, warehousemanagement system 210, computing device 600, computing clusters 609 a-c,or one or more other computing devices or systems, which may make up thecontrol system discussed with respect to FIGS. 7-12. The operations offlow chart 700 may be performed in real time, and some or all of themmay be repeated or updated periodically, for example, whenever updatedsensor data becomes available (e at a frequency of 50 Hz).

Block 702 may involve determining, by a control system, a path to befollowed by a vehicle through an environment. The path may comprise anordered sequence of positions. The vehicle may be any mobile roboticdevice capable of following the determined path.

FIG. 8A illustrates a top-down view of vehicle 800 and path 801determined for vehicle 800 to follow through an environment, in anexample embodiment. Vehicle 800 may be a pallet jack or fork truckhaving tines 802 and 804. Tines 802 and 804 may allow vehicle 800 tointeract with a pallet or another storage structure by placing the tinesinto slots within the pallet, thereby enabling pick-up, transportation,and drop-off of the pallet. Vehicle 800 may also include sensor 806 forscanning the environment, allowing for vehicle localization and obstacledetection within the environment, among other operations. Theenvironment may include therein a plurality of objects 808 a, 808 b, 808c, and 808 d (e.g., boxes or pallets).

Path 801 may run from (or may form part of a path running from) astarting position within the environment to target position within theenvironment. Path 801 may be planned around known or fixed obstacles(e.g., walls, pallet racks) in the environment based on kinematic anddynamic properties of vehicle 800. Path 801 may be made up of aplurality of discrete ordered positions 810, 812, 814, 816, 818, 820,822, and 824 (i.e., positions 810-824). Positions 810-824 may be targetpositions for vehicle 800 to follow in sequence to move along path 801.In some embodiments, path 801 may represent sections of one or moreroadmaps.

Before or while causing vehicle 800 to move along path 801, the controlsystem may analyze path 801 to determine whether the path is free ofobstacles. The analysis may involve using sensor 806 to scan the areasalong path 801 predicted to be occupied by the vehicle to identify anyobjects situated therein.

Referring back to FIG. 7, block 704 may involve determining, by thecontrol system, an intersection between a first object in theenvironment and a first area planned to be occupied by the vehicle whilemoving along the path.

In some implementations, determining the intersection between the firstobject and the first area may involve determining, by the controlsystem, for each respective position of the ordered sequence ofpositions along the path, a vehicle footprint indicating an area withina map of the environment to be occupied by the vehicle at the respectiveposition. The map may indicate the first object within the environment.However, in some implementations, the intersection between the firstobject and the first area may be determined in other ways, without usingvehicle footprints.

In some embodiments, the map may be determined based on data from sensor806, other sensors on other vehicles within the environment, or othersensors positioned at fixed locations within the environment. The mapmay represent a fusion of information from multiple different sensors,or from multiple different types of sensors. In some examples, the mapmay be a two-dimensional representation of the environment, and may bedetermined or updated by projecting representations of physical featureswithin the environment detected by the sensors onto a plane defined bythe two-dimensional representation of the environment. The map mayrepresent a threshold extent of the environment around the vehicle(e.g., a 10 meter by 10 meter square centered around the vehicle).Alternatively, the map may represent the environment in threedimensions, and may therefore represent a volume of space centeredaround the vehicle.

In some embodiments, the map may be represented as an occupancy gridthat includes a number of cells that represent corresponding areas inthe environment. The control system may develop the occupancy gridwithin a coordinate frame that corresponds to a point-of-view (POV) ofthe sensor (e.g., sensor 806). Each cell may be assigned a state thatindicates the status of the area represented by the cell. Particularly,a cell may be assigned as having an obstacle, free space, or unknown.Cells with obstacles may represent physical features within theenvironment, including fixed, movable, and mobile objects. Cells withfree space may be traversable by the vehicle without striking objects inthe environment. Unknown cells may require additional sensor data todetermine whether the area includes an obstacle or not (i.e., has freespace). The control system may periodically update and adjust theoccupancy grid based on new measurements of the environment from sensorscoupled to one or more vehicles navigating the environment.

FIG. 8B illustrates a plurality of vehicle footprints 811, 813, 815,817, 819, 821, 823, and 825 (i.e., footprints 811-825) projected alongpath 801 at corresponding positions 810, 812, 814, 816, 818, 820, 822,and 824, respectively. Footprints 811-825 are shown with alternatingline patterns for clarity. Each of footprints 811-825 indicates the areawithin the environment, or within the map representing the environment,that is planned to be occupied by vehicle 800 when vehicle 800 (e.g.,the centroid of vehicle 800) is at the respective position along path801. Footprint 811, for example, represents a first area within theenvironment planned to be occupied by vehicle 800 when the centroid ofvehicle 800 reaches position 810, while footprint 813 represents asecond area within the environment planned to be occupied by vehicle 800when the centroid of vehicle 800 reaches position 812, and so on.

The pose (i.e., position and orientation) of footprints 811-825 may bedetermined based on the physical size of vehicle 800 (e.g., mass andvolume), as well as the steering angles and velocities planned to becommanded to vehicle 800 to cause vehicle 800 to follow path 801. Insome embodiments, each footprint, in addition to representing the areain the environment expected to be occupied by the vehicle, may include abuffer region around the area. For example, each footprint might be 10%larger than an actual physical size of vehicle 800 to account for errorsin sensing, vehicle positioning, and simulation, among others.

In some embodiments, the density of positions 810-824, and thus thedensity of footprints 811-825, may be greater or smaller than that shownin FIGS. 8A-8E (i.e., additional positions may be included betweenpositions 810-824, or positions may be removed). Footprints 811-825 mayoperate as a filter to identify a subset of objects within theenvironment that constitute obstacles along path 801. That is,footprints 811-825 may be used to determine whether any of objects 808a-808 d constitute obstacles along path 801 with which vehicle 800 isexpected to collide.

Referring back to FIG. 7, determining the intersection between the firstobject and the first area in block 704, may, in some implementations,also involve determining, by the control system, that a first vehiclefootprint of the determined vehicle footprints intersects with the firstobject indicated by the map.

FIGS. 8B and 8C show that footprints 823 and 825 each intersect withobject 808 c. As vehicle 800 approaches position 822 along path 801,vehicle 800 is very likely to collide with object 808 c, potentiallycausing damage to vehicle 800 or object 808 c. In order to avoid such acollision, path 801 may be trimmed or shortened to prevent vehicle 800from coming within a threshold distance of object 808 a. Vehicle 800 maybe caused to slow to a stop as it approaches the end of the trimmedpath, thereby avoiding the collision with object 808 c.

Referring back to FIG. 7, block 706 may involve, in response todetermining the intersection between the first object and the firstarea, sequentially testing, by the control system, the ordered sequenceof positions to identify a first ordinal position in the orderedsequence of positions, where the first ordinal position corresponds to asecond area planned to be occupied by the vehicle while moving along thepath, where the second area is within a threshold distance of the firstobject, and where all areas planned to be occupied by the vehicle atpositions of the ordered sequence of positions preceding the firstordinal position are beyond the threshold distance of the first object.

FIG. 8C illustrates object 808 c, with which vehicle 800 is predicted tocollide, surrounded by a buffer 826 (i.e., an obstacle buffer). Thebuffer may be a circle having a radius equal to the threshold distance(i.e., a first threshold distance or a collision threshold distance).Alternatively, in some embodiments, the buffer may have a shape similarto the shape of the first object and may be offset from a perimeterthereof by the threshold distance. Thus, the buffer around object 808 c,for example, might be a square circumscribed around the circle making upbuffer 826. The buffer may be applied to any obstacles with which atleast one footprint is determined to intersect.

In some embodiments, the first threshold distance may be equal to orgreater than a maximum distance needed for vehicle 800 to come to astop, and may thus be based on physical and kinematic properties ofvehicle 800 (e.g., speed, mass, load carried, etc.). Buffer 826 may thusallow vehicle 800 to be stopped short of obstacle 808 c.

To avoid a collision between vehicle 800 and object 808 c, the controlsystem may determine the first ordinal footprint, and thus the firstordinal position along path 801, that falls within buffer 826 or anyother obstacle buffer. In FIG. 8C, portions of each of footprints 821,823, and 825 are within buffer 826, and are marked with alternatingpatterns to indicate this intersection with buffer 826. Footprint 821 isthe first ordinal footprint, and position 820 is thus the first ordinalposition, along path 801 that falls within buffer 826. Vehicle 800 maybegin to exceed a threshold risk of collision with object 808 c ifvehicle 800 reaches position 820 while moving along path 801.

The term “ordinal” is herein used to describe a position or index withinan ordered sequence or a subset thereof. Thus, for example, positions810, 812, and 814 represent a first, a second, and a third ordinalposition of positions 810-824 along path 801, respectively. Similarly,footprints 821, 823, and 825 represent a first, a second, and a thirdordinal footprint of a first subset of footprints 811-825, where thefirst subset includes only footprints intersecting with or locatedwithin buffer 826.

In an example embodiment, determining, from within ordered sequence ofpositions 810-824, the first ordinal position (i.e., position 820) whichcorresponds to a vehicle footprint (i.e., footprint 821) that is withinthe threshold distance of the first object may involve scanning oranalyzing positions 810-824 in sequence, starting with position 810 andmoving towards position 824, until a position whose correspondingfootprint intersects buffer 826 is found. In another embodiment, each ofpositions 810-824 may be associated with a numerically consecutive indexrepresenting the position's place within the ordered sequence 810-824.Accordingly, determining the first ordinal position may involveselecting, from a group of positions (e.g., 820, 822, and 824)corresponding to footprints (e.g., 821, 823, and 825) that intersectswith region 826, a position having a smallest index value (e.g., 820).

Notably, identifying the objects that intersect with the vehiclefootprints before applying the buffer regions, and applying the bufferregion to only the identified intersecting objects, allows an extent offalse-positive detections of collisions to be reduced. On the otherhand, applying buffer regions to all objects within the environment,regardless of their intersection with vehicle footprints, andsubsequently searching for intersections between the buffer regions andthe projected vehicle footprints to identify objects constitutingobstacles would result in numerous false-positive collision detections,and would thus unnecessarily impede progress of vehicle 800 through theenvironment.

Referring back to FIG. 7, block 708 may involve trimming, by the controlsystem, the path to remove, from the ordered sequence of positions, (i)the first ordinal position and (ii) any positions subsequent thereto.Trimming the path in this way may prevent the vehicle from reachingpositions which would result in the vehicle colliding with the firstobject, or coming within a threshold distance of colliding with thefirst object.

FIG. 8D illustrates path 801 trimmed to remove therefrom positions 820,822, and 824, resulting in a shortened path which includes positions810, 812, 814, 816, and 818. Upon reaching position 818 of the trimmedpath, vehicle 800 may be caused to stop to avoid moving to within buffer826 around obstacle 808 c.

Referring back to FIG. 7, block 710 may involve causing, by the controlsystem, the vehicle to stop at an end of the trimmed path. The vehiclemay remain stopped until the control system determines an alternativepath for the vehicle to follow, or, if a path around the obstacle is notavailable, the obstacle is cleared.

FIG. 8E illustrates planning of an alternative path to allow vehicle 800to drive around obstacle 808 c. The control system may determine aregion of available space 828 in the environment that is traversable byvehicle 800 to reach a target location to which path 801 originallylead. The control system may further determine one or more alternativepaths 830 and 832 for vehicle 800 to follow after the trimmed path andthrough region 828. For example, if vehicle 800 has already reached andstopped at position 818 at the time when region 828 is determined,vehicle 800 may be caused to follow alternative path 830 which followsfrom position 818. In another example, if vehicle 800 has not yetreached position 816 at the time when region 828 is determined, vehicle800 may be caused to follow alternative path 832 which follows fromposition 816.

In an example embodiment, once path 801 is trimmed, vehicle 800 mayrequest, from offboard planner 112 shown in FIG. 1, the region ofavailable space and the alternative paths. Vehicle 800 may determine,based data from sensor 806, for example, region 828 of free space thatvehicle 800 might use to navigate around obstacle 808 c. Vehicle 800 maythen request, from offboard planner 112, permission to occupy region828. Alternatively, offboard planner 112 may determine region 828.Offboard planner 112 may determine alternative paths 830 and 832 throughregion 828 while ensuring that these alternative paths do not intersectwith regions or paths assigned to other vehicles in the environmentmanaged by offboard planner 112. Further, motion of vehicle 800 alongpaths 830 or 832 may be synchronized with movements of the othervehicles in the environment to avoid collisions.

In some embodiments, region 828 and paths 830 and 832 may represent orcorrespond to sections or portions of a roadmap. For example, region 828may be mapped to one or more roads within a roadmap of the environment,and paths 830 and 832 may represent portions of the one or more roads.

In another example embodiment, the path determined by the control systemmay include an executable path portion and a tentative path portion. Theexecutable path portion may be determined to be free of obstacles andmay be commanded to be followed by the vehicle. The tentative pathportion might be a candidate path for the vehicle which may need to bescanned for obstacles before it is assigned to a vehicle as anexecutable path.

The control system may cause the vehicle to follow the executable pathportion and, while the vehicle follows the executable path portion,cause a sensor connected to the vehicle to scan the tentative pathportion to detect any obstacles situated along the tentative pathportion. If an obstacle is detected, the tentative path portion may betrimmed to remove therefrom any positions potentially resulting in acollision, as described above. In response, the control system maydetermine an alternative tentative path for the vehicle to scan andpotentially follow after the executable path portion or after thetrimmed tentative path portion, thus allowing the vehicle to avoid anyobstacles along the tentative path portion. In some embodiments, thealternative tentative path may be determined before the vehicle reachesthe end of the trimmed path, thus potentially allowing the vehicle toproceed through the environment without having to stop at the end of thetrimmed path.

In some instances, evaluating both the executable path portion and thetentative path portion may assist with detecting obstacles along thetentative path portion that result in both the tentative path portion aswell as a section of the executable path portion being trimmed. Namely,when an obstacle intersects the tentative path portion near thebeginning of the tentative portion, but does not intersect theexecutable path portion, the buffer around that obstacle may cause thecontrol system to trim the tentative path portion as well as theexecutable path portion. On the contrary, if the control system had notevaluated the tentative path portion for potential collisions untilafter the vehicle traversed the executable path portion, vehiclefootprints at or near the end of the executable path portion might betoo close to the obstacle (i.e., within the collision thresholddistance), thus resulting in the vehicle inadvertently coming within thecollision threshold distance.

In some embodiments, multiple tentative paths may be determined andanalyzed for collisions. Each of the multiple tentative paths may betrimmed according to the obstacles intersecting with the vehiclefootprints projected therefor. From the trimmed multiple tentativepaths, a longest tentative path or a tentative path that maximizes avehicle velocity through the environment may be selected to be executedby the vehicle.

In some instances, multiple obstacles may be determined to intersectwith one or more vehicle footprints. For example, in FIGS. 8A-8E, object808 d might be closer to path 801 and might therefore intersect withfootprints 819 or 821. In such a case, the collision avoidanceoperations herein described might be performed only for an obstacleclosest to a current position of vehicle 800 (i.e., obstacle 808 d) oran obstacle intersecting with a footprint associated with a lowestordinal position along the ordered sequence of positions 810-824, sinceperforming the operations for any other obstacles may be redundant. Thatis, the first obstacle along path 801 may necessitate path 801 to betrimmed to a greater extent than any other obstacle, and might be theonly one considered by the control system for a given path. Whenmultiple obstacles intersect with a same footprint (e.g., the footprintassociated with the lowest ordinal position along the ordered sequenceof positions 810-824), each of the multiple intersecting obstacles maybe considered in trimming the path. That is, the first ordinal positionmay be one that corresponds to a vehicle footprint that is within thethreshold distance of any one of the multiple intersecting obstacles.The path may thus be trimmed to stop the vehicle at least the bufferdistance away from the closest one of the multiple intersectingobstacles.

V. Example Vehicle Velocity Trajectories

In addition to stopping vehicle 800 at the end of the trimmed path toavoid collisions, the determined vehicle footprints 811-825 may be usedto manage a speed of the vehicle through the environment to allow forsafe traversal of the path. The control system may determine, for eachrespective position of the ordered sequence of positions along thetrimmed path, a target velocity for the vehicle. Notably, by projectingvehicle footprints 811-825 before vehicle 800 arrives at thecorresponding positions 810-824, vehicle 800 may be smoothly slowed to astop, thus preventing any objects carried by vehicle 800 from shifting,becoming unbalanced, or falling off. This approach may create smoothervelocity transitions than those resulting from a collision avoidancesafety system of vehicle 800 utilizing protective fields and warningfields.

FIG. 9 illustrates aspects of an example collision avoidance safetysystem of vehicle 800. The safety system might include protective fields900 a and 900 b in front of and behind vehicle 800, respectively, aswell as warning fields 902 a and 902 b in front of and behind vehicle800, respectively. Fields 900 a, 900 b, 902 a, and 902 b may be definedin software by the safety system. The safety system may be configured tocause vehicle 800 to travel under a threshold speed when an object isdetected within warning field 900 a or 900 b. Similarly, the safetysystem may be configured to cause vehicle 800 to come to a stop when anobject is detected within protective field 902 a or 902 b. Sizes offields 900 a, 900 b, 902 a, and 902 b may be scaled based on thevelocity of vehicle 800.

FIGS. 10A and 10B illustrate differences between velocity trajectoriesachieved by the safety system of vehicle 800 and the operationsdescribed with respect to FIGS. 7-8E. Vehicle 800 may initially becommanded to traverse points 810-824, as illustrated in FIGS. 8A-8C,according to velocity trajectory 1000, as shown in FIG. 10A. As vehicle800 traverses points 810-824, object 808 c may be determined to be anobstacle and thus vehicle 800 may be caused to come to a stop to avoidcolliding with object 808 c.

When vehicle 800 relies only on its safety system to avoid object 808 c,vehicle 800 may end up following velocity trajectory 1008 as it movesacross positions 810-824 and eventually comes to a stop before strikingthe obstacle. Because the safety system will not cause vehicle 800 toslow down until object 808 c enters one of warning fields 902 a or 902b, the safety system will begin to slow the vehicle at approximatelyposition 820, when object 808 c enters warning field 902 a. The rate ofdeceleration will increase as object 808 c enters protective field 900a, and vehicle 800 is forced to an abrupt stop before reaching position824.

On the other hand, when vehicle 800 relies on the control systemcarrying out the operations described with respect to FIGS. 7-8E,vehicle 800 may end up following velocity trajectory 1006 as it movesacross positions 810-818. The operations of flow chart 700 may beperformed before vehicle 800 reaches position 812, therefore identifyingobject 808 c as an obstacle much earlier than the safety system wouldusing the protective and warning fields. As a result of this earlyidentification of obstacle 808 c, vehicle 800 may be slowed to a stopwith a smaller average and instantaneous deceleration.

Notably, vehicle 800 may come to a stop from approximately the samevelocity over four position intervals (i.e., 810-812, 812-814, 814-816,and 816-818) when following velocity trajectory 1006 and less than twoposition intervals (i.e., 820-822 and part of 822-824) when followingvelocity trajectory 1008. In other words, the operations of flow chart700 increase a distance over which vehicle 800 is able to modulate itsvelocity to come to a stop to avoid colliding with obstacle 808 c,resulting in lower deceleration of vehicle 800 when compared with thesafety system. Thus, any payload carried by vehicle 800 may experiencefewer disturbances and vehicle 800 may be more likely to stop in time toavoid the obstacle, among other benefits.

In some implementations, the operations described with respect to FIGS.7-8E may be used to determine a velocity trajectory for vehicle 800 asit moves along a path, regardless of whether an obstacle is detectedthat intersects with footprints 811-825. Namely, vehicle speed buffersmay be placed around each object detected within the environment (e.g.,808 a-808 d). The vehicle speed buffers may be used to detect whetherany of footprints 811-825 are within a second threshold distance (i.e.,a speed threshold distance) of the objects within the environment, andmay be structured much like buffer 826. When the control systemdetermines, for example, that footprint 813 is situated within thesecond threshold distance of object 808 a, but does not intersect withobject 808 a itself, a speed of vehicle 800 at position 812 may belimited to a first speed limit. The first speed limit may reduce theprobability of any variations in positioning of vehicle 800 aroundposition 812 resulting in a collision with object 808 a, may allowvehicle 800 to comply with any relevant safety standards regarding theallowed speed of autonomous vehicles near objects within theenvironment, and may be used to slow vehicle 800 to a speed such thatany velocity-based protective and/or warning fields thereof do notintersect with object 808 a.

In some examples, the second threshold distance may be smaller than thefirst threshold distance so that the vehicle speed buffers are lesssensitive to detection of nearby vehicle footprints than the buffer 826.For example, the second threshold distance may be 50 centimeters and thefirst threshold may be 3 meters. Alternatively, the second thresholddistance may be equal to or greater than the first threshold distance.

Further, in some examples, the control system may be configured toclassify detected objects into a plurality of categories and determinethe first or second threshold distance for each object based on thecategory into which the object is classified. Classification may beperformed using, for example, a machine learning algorithm (e.g.,artificial neural networks applied to images from a ToF camera). Forexample, objects may be generally classified into fixed objects (e.g.,walls, pallet racks) and non-fixed objects (e.g., boxes, pallets,vehicles), with fixed objects assigned smaller threshold distances thannon-fixed objects. Object may also be classified into more specificcategories, such as pallet jack, human, pallet, box, stationary robot,etc., depending on the contents of the environment in which the vehicleis operating.

A pallet jack may be assigned larger threshold distances than, forexample, a pallet because the pallet jack includes tines protrudingtherefrom, whereas the pallet is generally not expected to have physicalfeatures protruding therefrom. Thus, the larger threshold may facilitateavoidance of the tines in the event that the tines, or a portionthereof, are not detected by sensors and indicated within the map of theenvironment. Further, in addition to classification, the control systemmay determine an orientation of the object, and determine the bufferregion based on the orientation. For example, an orientation of a palletjack located near the path may allow the control system to predict aposition of tines thereof, which might not be indicated on the map ofthe environment. In some embodiments, classification of the obstacleblocking the path may be used to determine a course of action foravoiding the obstacle (e.g., go around obstacle, wait for obstacle tomove, wait for operator, etc.).

Yet further, in some examples, the control system may be configured todetermine a task to be performed by the vehicle in the environment, anddetermine the first or second threshold distance based on the task. Forexample, when vehicle is carrying a load, the first and secondthresholds may be set at values larger than if the vehicle were movingwithout a load. The larger thresholds may provide additional clearancefor any portions of the load extending beyond the physical size of thevehicle, as well as additional stopping distance in the event anobstacles is detected. Increasing the size of the first and secondthresholds rather than placing a larger buffer around the vehiclefootprints may allow safer operation without increasing the number ofdetected potential collisions (e.g., false positives).

In some embodiments, obstacles may be classified into fixed (notmoveable), static (movable but not moving), or mobile (movable andmoving) obstacles. For mobile obstacles, the control system maydetermine expected paths of the mobile obstacles, and project footprintsof the mobile obstacles along the expected paths. The control system maythen determine whether any of the vehicle footprints intersect with anyof the obstacle footprints and apply buffers around any obstacle orobstacle footprints that intersect with at least one vehicle footprint.Further, in some examples, the expected obstacle path and the vehiclepath may be synchronized in time. The control system may thus determinewhether any of the obstacle footprints intersect with any of the vehiclefootprints in space and time, and apply buffers around obstacles orobstacle footprints that intersect with at least one vehicle footprintin both space and time.

VI. Example Applications of the Obstacle Avoidance Operations

FIGS. 11A, 11B, 11C and 12 illustrate example scenarios where theoperations herein described may improve obstacle detection and improvethroughput of vehicle operations within the environment. FIG. 11Aillustrates vehicle 1100 which, much like vehicle 800, may be commandedto follow path 1101 through an environment. Another vehicle 1102, havinga body 1104 and tines 1106 and 1108, may be situated within theenvironment. Path 1101 may, include an ordered sequence a positions1110, 1112, 1114, 1116, 1118, 1120, 1122, 1124, and 1126 (i.e.,positions 1110-1126) for vehicle 1100 to follow. Path 1101 starts with afirst section (e.g., positions 1110, 1112, and 1114) and ends with asecond section (e.g., positions 1122, 1124, and 1128) parallel,adjacent, and connected to the first section by a third section (e.g.,positions 1116, 1118, and 1120). That is, path 1101 doubles back onitself. Such paths may arise frequently in warehouse aisles, forexample.

In some embodiments, obstacles within the environment may be detectedbased on data from a sensor configured to detect obstacles along a firstplane parallel to and situated a first distance above a ground surfaceof the environment. The sensor may be, for example, a 2D Light Detectionand Ranging (LIDAR) device configured to rotate with respect to vehicle1100 and scan the environment along the first plane. Accordingly,physical features within the environment that are above or below thefirst plane might be undetected by the sensor and therefore not shown inthe map of the environment. For example, while body 1104 of vehicle 1102might intersect with the first plane and may therefore be detected,tines 1106 and 1108 might be situated below the first plane and maytherefore be undetected. In some embodiments, the system may use asensor with a field of view that encompasses tines 1106 and 1108.However, tines 1106 and 1108 may be positioned close to the ground andmay therefore still be difficult to detect. Nevertheless, the obstacleavoidance operations herein described may be used to allow vehicle 1100to avoid colliding with tines 1106 and 1108 of vehicle 1102.

A control system may determine, for each respective position of orderedsequence of positions 1110-1126 along path 1101, a vehicle footprintindicating an area within a map of the environment to be occupied by thevehicle at the respective position. Thus, the control system maydetermine footprints 1111, 1113, 1115, 1117, 1119, 1121, 1123, 1125, and1127 (i.e., footprints 1111-1127), as illustrated in FIG. 11B. Thecontrol system may also identify body 1104, but not tines 1106 and 1108,of vehicle 1102 as potential obstacles indicated within the map of theenvironment. The control system may further determine that footprints1123 and 1125 each intersect with body 1104 of vehicle 1102.Intersection of body 1104 with footprints 1123 and 1125 may thus serveas a proxy signal to indicate that body 1104 of vehicle 1102 constitutesan obstacle having difficult-to-detect parts protruding therefrom (i.e.,tines 1106 and 1108).

Notably, because tines 1106 and 1108 are not indicated in the map of theenvironment due to their positioning below the sensor's plane ofdetection, the control system might not determine that footprints 1113and 1115 intersect with tines 1106 and 1108. However, by utilizing asufficiently large buffer 1128 around body 1104 of vehicle 1102, tines1106 and 1108 may nevertheless be avoided by vehicle 1100. The thresholddistance defined by buffer 1128 may, for example, be based on thecontrol system classifying body 1104 of vehicle 1102 as a body of apallet jack. In response to this classification, the control system maydetermine a buffer within a threshold distance of the body that issufficiently large to encompass an expected size of tines 1106 and 1108.Alternatively, the threshold distance defined by buffer 1128 may bebased on a size of body 1104 (e.g., size of buffer 1128 may beproportional to a size of the detected obstacle), or may be apredetermined value, among other possibilities.

In response to determining that vehicle footprints 1123 and 1125intersect with vehicle body 1104, the control system may determine afirst ordinal position along the ordered sequence of positions whichcorresponds to a vehicle footprint that is within a threshold distanceof the first object. By scanning each footprint along path 1101, or byscanning only footprints within buffer 1128, the control system mayidentify vehicle footprint 1113 as a first ordinal footprint within thethreshold distance of the vehicle body 1104, and thus position 1112 asthe first ordinal position.

The control system may then trim path 1101 to remove therefrom position1112 and positions 1114-1127 subsequent to position 1112, as illustratedin FIG. 11C. Vehicle 1100 may be caused to traverse trimmed path 1101and may be caused to stop at position 1110, representing the end of thetrimmed path, to avoid vehicle 1102. Notably, tines 1106 and 1108 may beavoided in spite of not having been indicated on the map of theenvironment.

Notably, when the path to be followed by the vehicle is linear, thefirst ordinal position may be determined by selecting a position alongthe path that precedes, by the threshold distance, the position at whicha vehicle footprint first intersects with the obstacle (i.e., by“walking back” from the first vehicle footprint intersecting theobstacle by the threshold distance). Thus, buffer region 1128 might notneed to be determined or used for linear paths. However, when the pathis not linear (e.g., when the path doubles-back on itself like path1101), buffer region 1128 may be used to more accurately enforce thethreshold distance. For example, if buffer 1128 was not used, but ratherfootprint 1123 was “walked back” by the threshold distance, the controlsystem might identify one of positions 1118 or 1120 as the first ordinalposition, thus resulting in path 1101 not being sufficiently trimmed toavoid tines 1106 and 1108.

FIG. 12 illustrates how the obstacle detection and avoidance operationsherein described may allow for improved throughput in vehicle operationwhen compared with a vehicle safety system utilizing protective andwarning fields, as shown in FIG. 9. FIG. 12 shows vehicle 1200 movingthrough an environment along path 1210. Vehicle 1200 utilize a safetysystem that includes front warning field 1202 a and rear warning field1202 b, and which may also include protective fields, as shown in FIG.9. The environment includes walls 1212 and 1214 defining a corner of theenvironment. Footprints 1204, 1206 and 1208 represent past and futurepositions of vehicle 1200 along path 1210.

While traveling along path 1210, vehicle 1200 will not collide withwalls 1214 or 1212. However, warning fields 1202 a and 1202 b of vehicle1200 will intersect with walls 1214 and 1212, respectively, when vehicle1200 traverses the curved section of path 1210, as shown in FIG. 12. Thesafety system uses warning fields 1202 a and 1202 b to limit a speed ofvehicle 1200 to under a threshold speed limit when an object is detectedwithin warning field 1202 a or 1202 b. Thus, the safety system mightlimit the speed of vehicle 1200 to a speed below that with which vehicle1200 might have originally been commanded to traverse the curved sectionof path 1210. Notably, the speed of vehicle 1200 might be limited eventhough vehicle 1200 is not expected to collide with any obstacles alongpath 1210. Such limiting of the speed of vehicle 1200 by the safetysystem may reduce the throughput of vehicle 1200, thus increasing theoperating cost of a warehouse or other facility utilizing vehicles likevehicle 1200.

Accordingly, in some implementations, the control system may disable thewarning fields 1202 a and 1202 b of vehicle 1200 to increase an averagespeed of vehicle 1200 along path 1210. The control system may insteadcarry out the operations described with respect to FIGS. 7-11C to detectand avoid obstacles without inadvertently limiting a speed of vehicle1200. In some implementations, warning fields 1202 a and 1202 b may bedisabled by the control system when target velocities of a velocitytrajectory for vehicle 1200 to follow along path 1210 exceed thethreshold speed limit set by the warning fields. Further, in someexamples, the control system may determine the collision thresholddistance or the speed threshold distance to place around obstacles basedon a size of the area defined by the warning field or protective field.For example, the collision threshold distance or the speed thresholddistance may be proportional to the warning or protective field area, ormay be proportional to a length of the warning or protective field.

Notably, in some embodiments, the warning fields of the safety systemmight be determined internally by the safety system and might not bemodifiable by the control system. Thus, the warning fields might notoffer the same level of control and flexibility as the speed buffersplaced around obstacles. On the other hand, the speed buffers may allowthe control system to dynamically determine when to utilize the speedbuffers as well as the size thereof.

In some embodiments, rather than disabling the safety system of vehicle1200, the control system may work in cooperation with the safety systemto detect the obstacles that would otherwise be undetected by the safetysystem (e.g., due to the safety system not using data from some of theavailable sensors). Further, in some instances, the control system mayoperate to determine paths that do not trigger the safety system ofvehicle 1200, that is, paths that do not result in obstaclesintersecting with warning fields 1202 a and 1202 b, for example (or anyprotective fields associated with vehicle 1200). Thus, the vehicle mayoperate with two redundant systems operating to avoid collisions withobstacles.

VII. Additional Example Operations

In some embodiments, for each respective position of the orderedsequence of positions along the trimmed path, a target velocity may bedetermined for the vehicle to cause the vehicle to stop at the end ofthe trimmed path. The vehicle may be caused to follow the trimmed pathwith the determined target velocities.

In some embodiments, the ordered sequence of positions may include astarting position and an ending position. Sequentially testing theordered sequence of positions to identify the first ordinal position inthe ordered sequence of positions may involve: determining, for arespective position of the ordered sequence of positions and beginningwith the starting position, whether an area planned to be occupied bythe vehicle at the respective position is within the threshold distanceof the first object; when the area planned to be occupied by the vehicleat the respective position is not within the threshold distance of thefirst object, determining, for a subsequent respective position of theordered sequence of positions, whether an area planned to be occupied bythe vehicle at the subsequent respective position is within thethreshold distance of the first object; and when the area planned to beoccupied by the vehicle at the respective position is within thethreshold distance of the first object, determining that the respectiveposition is the first ordinal position.

In some embodiments, objects within the environment may be detectedbased on data from a sensor configured to detect objects along a firstplane parallel to and situated a first distance above a ground surfaceof the environment.

In some embodiments, the path may start with a first section and endwith a second section parallel, adjacent, and connected to the firstsection by a third section. Based on the data from the sensor, a map ofthe environment indicating the first object situated along the secondsection of the path may be determined. The first object may include aphysical feature extending into an area planned to be occupied by thevehicle at a corresponding position along the first section of the path.The physical feature may be situated above or below the first plane andmight not be indicated as an object in the map of the environment. Thephysical feature may be within the threshold distance of the firstobject. The second section, the third section, and a portion of thefirst section may be trimmed to avoid the physical feature of the firstobject.

In some embodiments, determining the intersection between the firstobject in the environment and the first area planned to be occupied bythe vehicle while moving along the path may involve determining, foreach respective position of the ordered sequence of positions along thepath, a vehicle footprint indicating a region within a map of theenvironment to be occupied by the vehicle at the respective position.The map may indicate the first object within the environment.Determining the intersection between the first object in the environmentand the first area planned to be occupied by the vehicle while movingalong the path may also involve determining that a first vehiclefootprint of the determined vehicle footprints intersects with the firstobject indicated by the map.

In some embodiments, each of the determined vehicle footprints mayinclude a buffer region around the region within the map to be occupiedby the vehicle at the respective position.

In some embodiments, a safety system of the vehicle may include awarning field defining an area around the vehicle. The safety system maybe configured to cause the vehicle to travel under a threshold speedwhen an object is detected within the warning field. A velocitytrajectory may be determined for the path. The velocity trajectory maydefine, for each respective position of the ordered sequence ofpositions along the path, a target velocity for the vehicle. A subset ofthe target velocities along the path may exceed the threshold speed ofthe warning field. The warning field of the safety system may bedisabled to increase an average speed of the vehicle along the path. Thethreshold distance around the first object may be determined based on asize of the area defined by the warning field.

In some embodiments, the threshold distance may be a first thresholddistance. It may be determined that a second area planned to be occupiedby the vehicle while moving along the path is situated within a secondthreshold distance of a second object. The second object might notintersect with any areas planned to be occupied by the vehicle whilemoving along the path. In response to determining that the second areais situated within the second threshold distance of the second object, aspeed limit may be determined for the vehicle at a position of theordered sequence of positions corresponding to the second area.

In some embodiments, objects within the environment may be detectedbased on data from a sensor and indicated on a map. The map may includea two-dimensional representation of the environment. Based on the datafrom the sensor, a physical feature within the environment may bedetermined. The map may be determined by projecting a representation ofthe physical feature onto a plane defined by the two-dimensionalrepresentation of the environment.

In some embodiments, the path to be followed by the vehicle through theenvironment may include an executable path portion determined to be freeof obstacles and a tentative path portion to be scanned for obstacles.The vehicle may be caused to follow the executable path portion. Whilethe vehicle follows the executable path portion, a sensor connected tothe vehicle may be caused to scan the tentative path portion and detectthe first object situated along the tentative path portion. Thetentative path portion may be trimmed to remove, from the orderedsequence of positions along the tentative path portion, (i) the firstordinal position and (ii) any positions subsequent thereto. Before thevehicle reaches the end of the trimmed path and in response todetermining the intersection between the first object situated along thetentative path portion and the first area, an alternative tentative pathmay be determined for the vehicle to follow after the executable pathportion to avoid the first object. The vehicle may be caused to followthe alternative tentative path.

In some embodiments, the path to be followed by the vehicle through theenvironment may include an executable path portion determined to be freeof obstacles and a tentative path portion to be scanned for obstacles.The tentative path portion may follow the executable path portion. Thevehicle may be caused to follow the executable path portion While thevehicle follows the executable path portion, a sensor connected to thevehicle may be caused to scan the tentative path portion and detect thefirst object situated along the tentative path portion. One or moreareas planned to be occupied by the vehicle at positions of the orderedsequence along the executable path portion may be within the thresholddistance of the first object. The tentative path portion and theexecutable path portion may be trimmed to remove, from the orderedsequence of positions along the tentative path portion and theexecutable path portion, (i) the first ordinal position along theexecutable path portion and (ii) any positions subsequent thereto.Before the vehicle reaches the end of the trimmed executable pathportion and in response to determining the intersection between thefirst object situated along the tentative path portion and the firstarea, an alternative tentative path may be determined for the vehicle tofollow after the trimmed executable path portion to avoid the firstobject. The vehicle may be caused to follow the alternative tentativepath.

In some embodiments, determining the intersection between the firstobject and the first area may involve determining a plurality of objectsthat intersect with one or more areas planned to be occupied by thevehicle while moving along the path. An object, from the plurality ofthe objects, closest to a current position of the vehicle may bedetermined as the first object.

In some embodiments, a task to be performed by the vehicle in theenvironment may be determined. The threshold distance may be determinedbased on the determined task.

In some embodiments, the first object may be classified into a categoryof a plurality of predefined categories. The threshold distance may bedetermined based on the category into which the first object isclassified.

In some embodiments, the path may lead to a target location. A region ofavailable space in the environment traversable by the vehicle to reachthe target location and avoid the first object may be determined. Analternative path for the vehicle to follow after the trimmed path may bedetermined. The alternative path may run through the region of availablespace, Motion of the vehicle along the alternative path may besynchronized with movements of other vehicles through the environment.The vehicle may be caused to follow the alternative path.

In some embodiments, the alternative path may be determined byselecting, from a roadmap graph, roadmap sections that lead to thetarget location. Similarly, the path to be followed through the vehiclethrough the environment may be defined by respective sections of theroadmap graph.

VIII. Conclusion

The present disclosure is not to be limited in terms of the particularembodiments described in this application, Which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its scope, as will be apparent to thoseskilled in the art. Functionally equivalent methods and apparatuseswithin the scope of the disclosure, in addition to those enumeratedherein, will be apparent to those skilled in the art from the foregoingdescriptions. Such modifications and variations are intended to fallwithin the scope of the appended claims.

The above detailed description describes various features and functionsof the disclosed systems, devices, and methods with reference to theaccompanying figures. The example embodiments described herein and inthe figures are not meant to be limiting. Other embodiments can beutilized, and other changes can be made, without departing from thespirit or scope of the subject matter presented herein. It will bereadily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

A block that represents a processing of information may correspond tocircuitry that can be configured to perform the specific logicalfunctions of a herein-described method or technique. Alternatively oradditionally, a block that represents a processing of information maycorrespond to a module, a segment, or a portion of program code(including related data). The program code may include one or moreinstructions executable by a processor for implementing specific logicalfunctions or actions in the method or technique. The program code and/orrelated data may be stored on any type of computer readable medium suchas a storage device including a disk or hard drive or other storagemedium.

The computer readable medium may also include non-transitory computerreadable media such as computer-readable media that stores data forshort periods of time like register memory, processor cache, and randomaccess memory (RAM). The computer readable media may also includenon-transitory computer readable media that stores program code and/ordata for longer periods of time, such as secondary or persistent longterm storage, like read only memory (ROM), optical or magnetic disks,compact-disc read only memory (CD-ROM), for example. The computerreadable media may also be any other volatile or non-volatile storagesystems. A computer readable medium may be considered a computerreadable storage medium, for example, or a tangible storage device.

Moreover, a block that represents one or more information transmissionsmay correspond to information transmissions between software and/orhardware modules in the same physical device. However, other informationtransmissions may be between software modules and/or hardware modules indifferent physical devices.

The particular arrangements shown in the figures should not be viewed aslimiting. It should be understood that other embodiments can includemore or less of each element shown in a given figure. Further, some ofthe illustrated elements can be combined or omitted. Yet further, anexample embodiment can include elements that are not illustrated in thefigures.

Additionally, any enumeration of elements, blocks, or steps in thisspecification or the claims is for purposes of clarity. Thus, suchenumeration should not be interpreted to require or imply that theseelements, blocks, or steps adhere to a particular arrangement or arecarried out in a particular order.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims.

What is claimed is:
 1. A method comprising: determining, by a controlsystem, a path to be followed by a vehicle through an environment,wherein the path comprises an ordered sequence of positions;determining, by the control system, an intersection between a firstobject in the environment and a first area planned to be occupied by thevehicle while moving along the path; in response to determining theintersection between the first object and the first area, sequentiallytesting, by the control system, the ordered sequence of positions toidentify a first ordinal position in the ordered sequence of positions,wherein the first ordinal position corresponds to a second area plannedto be occupied by the vehicle while moving along the path, wherein thesecond area is within a threshold distance of the first object, andwherein all areas planned to be occupied by the vehicle at positions ofthe ordered sequence of positions preceding the first ordinal positionare beyond the threshold distance of the first object; trimming, by thecontrol system, the path to remove, from the ordered sequence ofpositions, (i) the first ordinal position and (ii) any positionssubsequent thereto; and causing, by the control system, the vehicle tostop at an end of the trimmed path.
 2. The method of claim 1, furthercomprising: determining, for each respective position of the orderedsequence of positions along the trimmed path, a target velocity for thevehicle to cause the vehicle to stop at the end of the trimmed path; andcausing the vehicle to follow the trimmed path with the determinedtarget velocities.
 3. The method of claim 1, wherein the orderedsequence of positions comprises a starting position and an endingposition, and wherein sequentially testing the ordered sequence ofpositions to identify the first ordinal position in the ordered sequenceof positions comprises: determining, for a respective position of theordered sequence of positions and beginning with the starting position,whether an area planned to be occupied by the vehicle at the respectiveposition is within the threshold distance of the first object; when thearea planned to be occupied by the vehicle at the respective position isnot within the threshold distance of the first object, determining, fora subsequent respective position of the ordered sequence of positions,whether an area planned to be occupied by the vehicle at the subsequentrespective position is within the threshold distance of the firstobject; and when the area planned to be occupied by the vehicle at therespective position is within the threshold distance of the firstobject, determining that the respective position is the first ordinalposition.
 4. The method of claim 1, wherein objects within theenvironment are detected based on data from a sensor configured todetect objects along a first plane parallel to and situated a firstdistance above a ground surface of the environment.
 5. The method ofclaim 4, wherein the path starts with a first section and ends with asecond section parallel, adjacent, and connected to the first section bya third section, and wherein the method further comprises: determining,based on the data from the sensor, a map of the environment indicatingthe first object situated along the second section of the path, whereinthe first object includes a physical feature extending into an areaplanned to be occupied by the vehicle at a corresponding position alongthe first section of the path, wherein the physical feature is situatedabove or below the first plane and is not indicated as an object in themap of the environment, wherein the physical feature is within thethreshold distance of the first object, and wherein the second section,the third section, and a portion of the first section are trimmed toavoid the physical feature of the first object.
 6. The method of claim1, wherein determining the intersection between the first object in theenvironment and the first area planned to be occupied by the vehiclewhile moving along the path comprises: determining, for each respectiveposition of the ordered sequence of positions along the path, a vehiclefootprint indicating a region within a map of the environment to beoccupied by the vehicle at the respective position, wherein the mapindicates the first object within the environment; and determining thata first vehicle footprint of the determined vehicle footprintsintersects with the first object indicated by the map.
 7. The method ofclaim 6, wherein each of the determined vehicle footprints comprise abuffer region around the region within the map to be occupied by thevehicle at the respective position.
 8. The method of claim 1, wherein asafety system of the vehicle comprises a warning field defining an areaaround the vehicle, wherein the safety system is configured to cause thevehicle to travel under a threshold speed when an object is detectedwithin the warning field, and wherein the method further comprises:determining a velocity trajectory for the path, wherein the velocitytrajectory defines, for each respective position of the ordered sequenceof positions along the path, a target velocity for the vehicle, andwherein a subset of the target velocities along the path exceed thethreshold speed of the warning field; disabling the warning field of thesafety system to increase an average speed of the vehicle along thepath; and determining the threshold distance around the first objectbased on a size of the area defined by the warning field.
 9. The methodof claim 1, wherein the threshold distance is a first thresholddistance, the method further comprising: determining that a second areaplanned to be occupied by the vehicle while moving along the path issituated within a second threshold distance of a second object, whereinthe second object does not intersect with any areas planned to beoccupied by the vehicle while moving along the path; and in response todetermining that the second area is situated within the second thresholddistance of the second object, determining a speed limit for the vehicleat a position of the ordered sequence of positions corresponding to thesecond area.
 10. The method of claim 1, wherein objects within theenvironment are detected based on data from a sensor and are indicatedon a map, wherein the map comprises a two-dimensional representation ofthe environment, and wherein the method further comprises: detecting,based on the data from the sensor, a physical feature within theenvironment; and determining the map by projecting a representation ofthe physical feature onto a plane defined by the two-dimensionalrepresentation of the environment.
 11. The method of claim 1, whereinthe path to be followed by the vehicle through the environment comprisesan executable path portion determined to be free of obstacles and atentative path portion to be scanned for obstacles, and wherein themethod further comprises: causing the vehicle to follow the executablepath portion; while the vehicle follows the executable path portion,causing a sensor connected to the vehicle to scan the tentative pathportion and detect the first object situated along the tentative pathportion; trimming the tentative path portion to remove, from the orderedsequence of positions along the tentative path portion, (i) the firstordinal position and (ii) any positions subsequent thereto; before thevehicle reaches the end of the trimmed path and in response todetermining the intersection between the first object situated along thetentative path portion and the first area, determining an alternativetentative path for the vehicle to follow after the executable pathportion to avoid the first object; and causing the vehicle to follow thealternative tentative path.
 12. The method of claim 1, wherein the pathto be followed by the vehicle through the environment comprises anexecutable path portion determined to be free of obstacles and atentative path portion to be scanned for obstacles, wherein thetentative path portion follows the executable path portion, and whereinthe method further comprises: causing the vehicle to follow theexecutable path portion; while the vehicle follows the executable pathportion, causing a sensor connected to the vehicle to scan the tentativepath portion and detect the first object situated along the tentativepath portion, wherein one or more areas planned to be occupied by thevehicle at positions of the ordered sequence along the executable pathportion are within the threshold distance of the first object; trimmingthe tentative path portion and the executable path portion to remove,from the ordered sequence of positions along the tentative path portionand the executable path portion, (i) the first ordinal position alongthe executable path portion and (ii) any positions subsequent thereto;before the vehicle reaches the end of the trimmed executable pathportion and in response to determining the intersection between thefirst object situated along the tentative path portion and the firstarea, determining an alternative tentative path for the vehicle tofollow after the trimmed executable path portion to avoid the firstobject; and causing the vehicle to follow the alternative tentativepath.
 13. The method of claim 1, wherein determining the intersectionbetween the first object and the first area comprises: determining aplurality of objects that intersect with one or more areas planned to beoccupied by the vehicle while moving along the path; and determining,from the plurality of the objects, an object closest to a currentposition of the vehicle as the first object.
 14. The method of claim 1,further comprising: determining a task to be performed by the vehicle inthe environment; and determining the threshold distance based on thedetermined task.
 15. The method of claim 1, further comprising:classifying the first object into a category of a plurality ofpredefined categories; and determining the threshold distance based onthe category into which the first object is classified.
 16. The methodof claim 1, wherein the path leads to a target location, and wherein themethod further comprises: determining a region of available space in theenvironment traversable by the vehicle to reach the target location andavoid the first object; determining an alternative path for the vehicleto follow after the trimmed path, wherein the alternative path runsthrough the region of available space, and wherein motion of the vehiclealong the alternative path is synchronized with movements of othervehicles through the environment; and causing the vehicle to follow thealternative path.
 17. A system comprising: a vehicle; and a controlsystem configured to: determine a path to be followed by the vehiclethrough an environment, wherein the path comprises an ordered sequenceof positions; determine an intersection between a first object in theenvironment and a first area planned to be occupied by the vehicle whilemoving along the path; in response to determining the intersectionbetween the first object and the first area, sequentially test theordered sequence of positions to identify a first ordinal position inthe ordered sequence of positions, wherein the first ordinal positioncorresponds to a second area planned to be occupied by the vehicle whilemoving along the path, wherein the second area is within a thresholddistance of the first object, and wherein all areas planned to beoccupied by the vehicle at positions of the ordered sequence ofpositions preceding the first ordinal position are beyond the thresholddistance of the first object; trim the path to remove, from the orderedsequence of positions, (i) the first ordinal position and (ii) anypositions subsequent thereto; and cause the vehicle to stop at an end ofthe trimmed path.
 18. The system of claim 17, wherein the orderedsequence of positions comprises a starting position and an endingposition, and wherein the control system is configured to sequentiallytest the ordered sequence of positions to identify the first ordinalposition in the ordered sequence of positions by: determining, for arespective position of the ordered sequence of positions and beginningwith the starting position, whether an area planned to be occupied bythe vehicle at the respective position is within the threshold distanceof the first object; when the area planned to be occupied by the vehicleat the respective position is not within the threshold distance of thefirst object, determining, for a subsequent respective position of theordered sequence of positions, whether an area planned to be occupied bythe vehicle at the subsequent respective position is within thethreshold distance of the first object; and when the area planned to beoccupied by the vehicle at the respective position is within thethreshold distance of the first object, determining that the respectiveposition is the first ordinal position.
 19. A non-transitory computerreadable storage medium having stored thereon instructions that, whenexecuted by a computing device, cause the computing device to performoperations comprising: determining a path to be followed by a vehiclethrough an environment, wherein the path comprises an ordered sequenceof positions; determining an intersection between a first object in theenvironment and a first area planned to be occupied by the vehicle whilemoving along the path; in response to determining the intersectionbetween the first object and the first area, sequentially testing theordered sequence of positions to identify a first ordinal position inthe ordered sequence of positions, wherein the first ordinal positioncorresponds to a second area planned to be occupied by the vehicle whilemoving along the path, wherein the second area is within a thresholddistance of the first object, and wherein all areas planned to beoccupied by the vehicle at positions of the ordered sequence ofpositions preceding the first ordinal position are beyond the thresholddistance of the first object; trimming the path to remove, from theordered sequence of positions, (i) the first ordinal position and (ii)any positions subsequent thereto; and causing the vehicle to stop at anend of the trimmed path.
 20. The non-transitory computer readablestorage medium of claim 19, wherein the ordered sequence of positionscomprises a starting position and an ending position, and whereinsequentially testing the ordered sequence of positions to identify thefirst ordinal position in the ordered sequence of positions comprises:determining, for a respective position of the ordered sequence ofpositions and beginning with the starting position, whether an areaplanned to be occupied by the vehicle at the respective position iswithin the threshold distance of the first object; when the area plannedto be occupied by the vehicle at the respective position is not withinthe threshold distance of the first object, determining, for asubsequent respective position of the ordered sequence of positions,whether an area planned to be occupied by the vehicle at the subsequentrespective position is within the threshold distance of the firstobject; and when the area planned to be occupied by the vehicle at therespective position is within the threshold distance of the firstobject, determining that the respective position is the first ordinalposition.